Who’s running to replace Ken Buck in Colorado’s Fourth Congressional District?

Caitlyn Kim/CPR News
Colorado Republican U.S. Rep. Ken Buck speaks with reporters about the House speaker selection process Tuesday, Oct. 24, 2023.

Updated April 21, 2024 at 7:02 a.m.

The announcement that GOP Rep. Ken Buck would not seek another term in office, has set off a heated primary to fill a rare vacancy in the reddest district in Colorado.

In late December 2023, the race gained even more prominence when Republican Rep. Lauren Boebert, who represents the 3rd Congressional District, said she would abandon plans to run for reelection there and instead seek the seat in the 4th.

The district is the most Republican in the state, with a +26 point lean, according to the Colorado Congressional Redistricting Committee. That means whoever wins the GOP primary will likely be on an easy glide path to Congress. A Democrat last won the seat in 2008, when its boundaries made it somewhat less politically lopsided, but only served for one term before the district flipped back into Republican control.

CO-04 encompasses most of the Eastern Plains, but its population centers are along the Front Range, including the suburban cities of Highlands Ranch, Parker, and Castle Rock to the south and Loveland and Wellington to the north.


Lauren Boebert

The far-right firebrand has served two terms in Congress representing a district on the other side of the state. Facing a tough reelection in CO-03, Boebert shocked many by announcing she’d run in the more solidly red CO-04

“It’s the right move for me personally and it’s the right decision for those who support our conservative movement,” she said in a video announcement in late December. Still, some of her fellow Republicans in the 4th district have already labeled her a carpetbagger for switching to run in a safer seat.

Boebert moved to Windsor, located in the 4th district, early in the new year. She also won top line at the district assembly, solidifying her front-runner position in the primary.

A member of the hard-right Freedom Caucus, Boebert was part of a bloc opposed to Kevin McCarthy during his Speaker’s race and pushed for changes in how the House operates, like ensuring 72 hours to read a bill and allowing one member to bring a motion to vacate against the Speaker.

Boebert, who spent most of 2023 fundraising for a tight race in her current seat, started 2024 with  a large campaign war chest and high name recognition, which could both help and hurt her. While she’s grown her social media fame pushing culture war issues, like anti-trans policies and pro-gun bills, she’s also garnered a lot of press for her behavior, not her legislation, from heckling President Joe Biden during a State of the Union address to suggesting a Muslim member of Congress was a terrorist to getting ejected from a performance of “Beetlejuice” while on a date.

Deborah Flora

The conservative KNUS radio show host once again put the microphone aside to run for public office. 

Flora, who lives in Parker, entered the 2022 U.S. Senate race but didn’t make the ballot for the Republican primary. She has also been active on education issues, helping found Parents United America, which advocates for parental rights and educational freedom. 

On social media, she said Colorado needs a “conservative fighter who will protect our children from woke indoctrination, defend our constitutional rights, and fight back against [President Joe] Biden’s radical agenda.” Flora’s campaign announcement focused on issues such as government spending, inflation, a secure border, and energy independence. 

Flora jumped into the race in early November and since then has raised more than $350,000. As of March 31, 2024, she had more than $165,000 cash on hand.

She made the ballot via petition.

Richard Holtorf

The rancher and Army veteran, who lives in Akron, currently serves in the state House representing a portion of the northeastern plains. He launched his bid for Congress from a livestock auction near his home, billing himself as a “no-nonsense conservative.” 

In his announcement, Holtorf said Congress is full of “doormats” who don’t stand up for conservative values. He also took Buck to task for not pushing the “Trump agenda.”

“Leadership is lacking in Congress,” he said in a release. “I’m a fighter who is ready to shake up the swamp, not become part of it.”

He currently holds a leadership position in the state legislature, serving as the caucus’s minority whip. He also sits on two committees: Agriculture, Water & Natural Resources and Public & Behavioral Health & Human Services. He has focused on the urban-rural divide during his tenure at the statehouse. 

He made the ballot by collecting signatures and getting more than 10 percent of delegates at the district assembly.

Holtorf’s tenure at the statehouse hasn’t always been smooth though. He dropped his firearm in a public area outside the House chamber and was reprimanded for using a racial slur during a heated discussion on the House floor in 2021.

He filed paperwork to run in early November and has raised $142,000 since then, including $38,000 he loaned to his campaign. As of the latest campaign finance filing, Holtorf has just under $100,000 cash on hand.

Mike Lynch

First elected to the General Assembly in 2020 to represent parts of Larimer and Weld counties, Lynch served as the chamber’s Minority Leader for the 2023 session, but stepped down from the leadership role under pressure on Jan 24, 2024, a week after news broke that he had been arrested for a DUI in 2022. 

Lynch, who qualified for the ballot via petitions, said he’s running for Congress for the same reason he ran for the statehouse, to get things done on issues of importance, like tackling the fentanyl epidemic.

“I think my voting record speaks for itself. And I also have figured out how to get bills passed,” he said, noting a number of his proposals have become law, despite Democratic control of the legislature. “I like the job of legislating. And obviously being in the minority, you have to learn how to get things done even though the odds aren’t in your favor, kind of a constant Mission Impossible.”

The U.S. Army veteran, who graduated from West Point and currently lives in Wellington, jumped into the race in early January.

He will continue to serve at the State House for the 2024 session, saying he doesn’t expect the campaign demands to be particularly different from running to retain his current seat.

Lynch has only raised over $40,000 and has just over $3,000 cash on hand.

Jerry Sonnenberg

The Sterling, Colorado, native served in the legislature, both in the House, where he was first elected in 2006, and then the Senate, where he reached the role of Senate President Pro Tem, before becoming a Logan County Commissioner in 2022.

Sonnenberg qualified for the ballot via signatures and getting more than 10 percent of the delegate vote at the district assembly.

In announcing his bid, the rancher pointed to challenges he said are a result of President Joe Biden and “liberals” — from migrants at the southern border and inflation to global instability. “In every corner of CD4, voters deserve a fighter who will show up for them, listen to their voice, and bring conservative policies that work for all of us to Washington, D.C.," he said in a statement. 

Among the issues Sonnenberg said he would focus on are combating “Bidenomics,” securing the border, and energy independence.

Sonnenberg got into the race in early December. Thus far, he raised over $310,000 and has just under $225,000 cash on hand.

Peter Yu

The Weld County Republican filed his paperwork for a congressional run in late December.

The son of immigrants, Yu, a businessman, worked in corporate America as a finance and mortgage consultant. He has never held public office, but has run twice. He lost the 2018 race against Democrat Joe Neguse for Colorado’s 2nd Congressional District and in 2022, he was one of many Republicans who entered the race to challenge Democrat Sen. Michael Bennet, but did not make the primary ballot.

On his website, Yu said he wants “to represent the people and preserve the Constitution, so that everyone can enjoy the freedom.” He also promised to put politics aside to help people and hold sessions with the community so they can provide him feedback.  The issues he highlighted include immigration reform and border security, energy independence, the debt and agriculture.

You raised about $285,000 but almost all of that was money he put into the campaign. Still, it means he currently has about $275,000 cash on hand.


Trisha Calvarese

Calvarese, who described herself as the “hometown” candidate, snagged the topline at the district assembly with almost 58 percent of the delegate vote. She was raised in Highlands Ranch and has worked as a speechwriter for groups like the National Science Foundation and AFL-CIO. While this is her first time as a candidate, she was a campaign manager for a House race in 2018. Her candidate lost.

In her announcement, Calvarese said she’ll offer a fresh, dynamic approach and contrasted herself to Boebert on numerous issues, such as supporting the bipartisan infrastructure law and the CHIPS and Science Act.  She added she “will defend freedoms like choice and access to reproductive care while working to expand opportunities in education and workforce training, especially in the rural part of the district.“

She was also selected by the vacancy committee to be the party’s nominee for the special election to fill the rest of Buck’s current term in Congress.

Ike McCorkle

This is McCorkle’s third try for the seat; he qualified this time by petitioning on to the ballot. The former Marine faced off against Buck in 2020 and 2022, losing each time by double digits in this solidly red district.  He said he’s running to “represent and fight for working families.”  

On his campaign website, McCorkle said “trust and confidence in government must be restored… He will listen to Colorado’s citizens, will turn aside improper and immoral financial offers, and will fight for what is best for Colorado, America, and the world.”

At the start of 2024, McCorkle had more than $311,000 in campaign cash on hand.

John Padora, Jr.

Padora qualified for the ballot by getting more than 30 percent of the vote at assembly. He describes himself as a manufacturing engineer, addiction recovery advocate, and progressive. He’s also been public about his experiences as a recovering drug addict

Padora said he’s a working-class person who will fight for working families and Coloradans, “not special interests in DC or companies based out of other states.” He added he thinks he can do better than other Democratic primary candidates to motivate the base and create support.

He recently moved to Severance, Colorado, from Pennsylvania, where he ran unsuccessfully for the statehouse in 2020. He starts 2024 with $29,000 cash on hand.

Other Party Candidates: 

Douglas Mangeris

The Loveland resident filed paperwork to run for the seat as a Libertarian, but does not appear to have a campaign website or social media and has not yet responded to a request from CPR for more information about his candidacy.

Dropped out:

Mariel Bailey (Republican): A former congressional staffer from Highlands Ranch, Bailey filed paperwork to run for Congress in mid-December and exited the race Jan. 25, 2024. Most recently, she worked for GOP Rep. Dan Crenshaw of Texas, but also spent time working for Reps. Victoria Spartz, R-IN, and Nicole Malliotakis, R-NY. She got her start interning for two Colorado lawmakers, former Rep. Mike Coffman and former Sen. Cory Gardner.

Floyd Trujillo (Republican): The Commerce City Republican failed to make ballot after falling short of signatures. A former Marine, he spent most of his career in the oil and natural gas industry. He was part of the Hispanic Community Energy Forum and headed former President Trump's Hispanic outreach effort in 2016.

Ted Harvey (Republican): Harvey was the only candidate to pin all of his hopes on the assembly process, but failed to reach the 30 percent threshold in delegate support to make the ballot.

First selected to fill a vacancy in the Colorado House of Representatives in 2001, Harvey was elected to two more terms in that chamber before winning a seat in the State Senate, where he served until 2015. He’s spent the years since then as a political consultant and recently served as chairman of the Committee to Defeat the President PAC, which endorsed Donald Trump’s 2024 campaign.

The Highlands Ranch Republican entered the race on Dec. 6, making the announcement at a meeting of the Parker Conservatives in Douglas County. 

“With the devastating moral and economic decay in our government, and with no proven or experienced conservative fighter willing to run for this critical seat, I’m running to make sure ‘We the People’ have a leader who will fight for us and stop the corrupted establishment insiders in both parties who are hell bent on destroying our Republic,” he said in a statement.

While he blasted Biden and House Democrats, Harvey also criticized other Republicans in his announcement, saying there are too many in the party who “talk a good game during the primary” but have never stood up to their leadership, taken on the “liberal media” or fought for conservative values.

Harvey, who got into the race in early December, started 2024 with $39,000 cash on hand.

Chris Phelen (Republican): The Castle Rock Republican suspended his campaign in mid-April, citing the need "to reduce the field to one candidate who can defeat divisive Lauren Boebert."

The businessman is a former staffer for Rep. Doug Lamborn, who represents the neighboring 5th district. Phelen worked as a staffer from 2007 to 2010 and then served as Lamborn’s chief of staff for three more years. After that, Phelen co-founded a venture development firm. 

When announcing his run in January, Phelen said he entered the race because he’s a servant at heart and “understands the nuances of the Congressional political system and would work with all parties to enact fiscally responsible legislation.”

“As your elected official, I will never lose sight of my responsibility to you, your families, and our communities, state, and country,” he said.

Trent Leisy (Republican): In early March, Leisy said he was suspending his congressional campaign and instead would run for Colorado House District 65, currently held by Mike Lynch, who is also running to replace Buck. 

Leisy first entered the race with the intention of primarying Buck, after the incumbent opposed Ohio Rep. Jim Jordan’s attempt to become Speaker. He’s currently a member of the five-person Weld County Council, after being appointed to the seat in May 2023 following a resignation.

Leisy said he spent four years in the U.S. Navy and describes himself as a small business owner, starting a corn seed operation as well as a social media company called FyreFox Media, which promotes the America First agenda.

Leisy is a backer of former President Donald Trump; he sports a “MAGA King” hat in some of his photos on social media and describes himself as an “America First Candidate” for the district. 

Justin Schreiber (Republican): While he filed paperwork to run, Schreiber didn’t submit petitions or turn up at assembly and failed to make serval candidate forums.  The self-described real estate investor and U.S. Army veteran entered the race in June, but has not shown any money raised since then through FEC filings. Schreiber did sign a pledge to support term limits in Congress. In a Ballotpedia candidate filing he wrote, “I don’t tolerate tyrants! I'm running to restore the constitution fully, dismantle the IRS, ATF, and FBI they are domestic terrorists.”

Karen Breslin (Democrat): An Elbert County resident, Breslin is a lawyer and political science instructor at the University of Colorado Denver. She failed to get enough support at the district assembly to qualify for hte ballot.

She said her campaign is focused on economic fairness. In a video announcement, she said “I’m deeply concerned about the inequities that rural communities experience around things like maternal health care, lack of food security…that too is something that government policy can address.”

Anil Saxena (Democrat): The first-time candidate from Parker filed paperwork to run in January. He never appeared to have a campaign website or social media. Saxena's LinkedIn page says he’s a partner at ServiceNow, a software company.