Gardner had withheld his endorsement from Trump and even got into a Twitter war with the billionaire, who is now the Republican presidential nominee. The dustup happened after Trump complained about the outcome of Colorado's GOP nominating process in April. Sen. Ted Cruz won that contest.
Now, Gardner says it's important to elect "the entire Republican ticket." Every seat in the House and 34 in the 100-member Senate are on the ballot. The Nov. 8 elections will decide whether Republicans keep control of both chambers.
Gardner first made comments about supporting Donald Trump during a fundraiser in Colorado Springs on Friday night. They were initially reported by the Colorado Springs Gazette.