Incumbent Democratic U.S. Sen. Michael Bennet, left, will face Republican challenger Darryl Glenn, right, in this fall's election.

(AP Photos)

Fundraising and TV advertising will be at the heart of this year’s U.S. Senate race and, so far, Democrat Michael Bennet is ahead.

Bennet has nearly $8.9 million in ads aired or scheduled through election day on Colorado television, cable and satellite channels.

All told, the Democrat has spent $6.5 million and still has about $5.7 million in the bank, as of June 8.

Glenn raised only about $137,000 for his campaign while spending about $16,500 of his own money, according to Federal Election Commission reports. But outside groups kicked in more than $600,000 to support Glenn and they spent about a third of that on TV .

But in periodic reports of large contributions filed after June 8, Glenn picked up fundraising steam, reporting another $50,300 in contributions through June 24. That included a $5,000 donation from former vice presidential candidate Sarah Palin’s PAC and $2,700 from Foster Friess, an influential Republican donor.

Bennet took in $264,350 between June 8 and June 24, according to FEC reports.

Republican Primary Spending

Altogether, the five candidates in the Republican Senate primary raised $4.3 million for their campaigns through June 8.

That includes at least $1.5 million that second-place finisher and former Colorado State University athletic director Jack Graham spent on his campaign and $1 million that third-place finisher Colorado Springs businessman Robert Blaha loaned to his campaign. Fourth-place finisher former state Rep. Jon Keyser spent at least $215,000 of his own money, including $60,000 he kicked in on June 20.

Here’s a look at total U.S. Senate fundraising and spending through June 8 based on Federal Election Commission filings:

The four Republican candidates who petitioned onto the ballot --  Blaha, Ryan Frazier, Graham and Keyser -- spent $1.7 million on TV ads in the six weeks before Tuesday’s primary. That’s according to an analysis of TV ad buy contracts from the Federal Communications Commission and Comcast Spotlight.

Glenn, the only candidate nominated by the Republican assembly in April, didn’t buy his own ads. But the national super PAC Senate Conservatives Action spent more than $190,000 promoting Glenn, mostly in Colorado Springs.

And Colorado Conservatives PAC spent nearly $20,000 on ads backing Keyser in the Denver cable market.

That nearly $2 million for TV ads in the Republican primary compares to Bennet’s nearly $1.6 million in ad spending during the same six weeks.

Here’s a look at the advertising spending in the Senate race from May 17 through Tuesday:

Including the TV ads, four outside groups reported spending more than $600,000 to support Glenn in the primary. They also paid for digital ads, telemarketing and direct mail to support the winning candidate.

TV Ads Won’t Stop

Those hoping for a respite to TV advertising after Tuesday’s primary won’t get it.

More than $50 million in ads have run or been reserved through election day on Colorado TV stations, cable and satellite networks.

PAC Priorities USA, which supports Democratic presidential candidate Hillary Clinton,  is the top spender thus far, with nearly $12 million worth of ads scheduled to run through Nov. 8.

Clinton started airing ads in mid-June and has purchased time through late July.