With Colorado Rep. Cory Gardner vacating his 4th District seat to run for Senate , Weld County District Attorney Ken Buck is dropping his Senate bid to vie for Gardner’s open seat.  

The maneuver partially clears the primary field for Gardner, while giving Buck a better shot at coming to Congress. Buck won the GOP Senate nomination in 2010 before losing to Democratic Sen. Michael Bennet.  

“Ken has decided to step aside because Cory is in a potentially stronger position to pick up the seat,” Buck consultant Walt Klein told CQ Roll Call.  

But, he added, “there’s no deal” between the two men to swap places on the ballot. The 4th District , which encompasses the eastern portion of Colorado, is solidly Republican. The open-seat race could invite a competitive and possibly crowded primary, though the filing deadline is just more than a month away, on March 31. A Colorado Republican source named state Sen. Scott Renfroe as a possible candidate, but noted that Buck would begin the race as the front-runner.  

Buck entered the Republican Senate primary in August  after a bout with cancer . Recently, the Tea Party Express passed Buck over for its Senate endorsement, instead backing state Sen. Owen Hill.