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 BennetNFL player points to Charlottesville after national anthem protest Trump quietly putting his stamp on the courts Overnight Energy: Senate begins moving energy nominations | Interior watchdog probing Zinke calls 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 GardnerScarborough: Trump has chosen the 'wrong side' Moore, Strange advance in Alabama GOP primary GOP senator: Nazis should 'go back to their hole' 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 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 CantorEx-RNC spokesman: After Trump remarks how can I tell minorities to vote GOP Kelly’s challenge? Bringing stability to Trump White House Special interests hide behind vets on Independence Day 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.