Ken Buck is likely headed to Washington after all. 

The 2010 Senate nominee, who was maligned in his race four years ago against Sen. Michael BennetMichael Farrand BennetDurbin: Senators to release immigration bill Wednesday Trump's 's---hole' controversy shows no sign of easing Dem senator: 'No question' Trump's 's---hole countries' comment is racist MORE (D-Colo.), won the open 4th District House GOP primary Tuesday night. Now, Buck is the odds-on favorite in the fall to succeed Rep. Cory GardnerCory Scott GardnerDurbin: Senators to release immigration bill Wednesday GOP senators eager for Romney to join them Gardner: Bipartisan DACA solution possible despite Trump's 's---hole countries' comment MORE (R-Colo.), who is running for Senate. 

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The Associated Press has called the race for Buck, who had 44 percent of the vote with 58 percent of precincts reporting. Buck's closest opponent, state Sen. Scott Renfroe, took just 24 percent despite winning the top spot on the ballot at the district convention. 

Still, Buck was perceived to be the favorite headed into the primary. He had originally been seeking to unseat Sen. Mark UdallMark Emery UdallDemocratic primary could upend bid for Colorado seat Picking 2018 candidates pits McConnell vs. GOP groups Gorsuch's critics, running out of arguments, falsely scream 'sexist' MORE (D-Colo.) this year but dropped out of the race when Gardner announced his candidacy. Gardner himself endorsed Buck to succeed him shortly after entering the Senate race.

Along with Gardner's endorsement, Buck had outraised all of his primary opponents, collecting more money than his three competitors combined. Supporters donating to Buck's campaign were the KochPAC, linked to billionaire brothers David and Charles Koch, and outgoing House Majority Leader Eric CantorEric Ivan CantorEric Cantor: Moore ‘deserves to lose’ If we want to make immigration great again, let's make it bipartisan Top Lobbyists 2017: Hired Guns MORE's (R-Va.) leadership PAC.

Buck will go on to face Democrat Vic Meyers and Libertarian nominee Jess Loban in the general election, but he’s expected to easily win in the GOP-leaning district.