District Attorney George Brauchler speaks as he an other community members honor Aurora theater shooting victim Veronica Moser Sullivan on Sept. 5. AAron Ontiveroz AFP/Getty

District Attorney George Brauchler’s decision to sit out the Senate race in Colorado is the latest in a string of blows to the GOP's chances in a key 2016 swing state.

Brauchler announced Wednesday that he would run for reelection as DA in his judicial district instead of challenging Democratic Sen. Michael Bennet. The news was first reported by KUSA-TV in Denver.

National Republicans’ first choice for the race, Rep. Mike Coffman, said in June that he wouldn't run statewide, party leadership turned its attention to Brauchler, who just this summer finished pro­sec­ut­ing the high-pro­file murder case of Au­rora movie theat­er shoot­er James Holmes. Brauchler met with members of the Colorado congressional delegation and made himself available for numerous interviews over the last few weeks as he deliberated his future.

“Despite the overwhelming support and encouragement that I received over the past few weeks, I have decided that now is not the right time for me and my family for me to make a run for the United States Senate," Brauchler said in a statement provided to National Journal. "I have decided instead to seek reelection as the district attorney for the 18th Judicial District." 

A Republican operative familiar with Brauchler’s decision said “serious family health issues” were recently discovered, noting “It is a very sad situation."

With Brauchler out, the Republican field to face Bennet includes: conservative state Sen. Tim Neville, Colorado Springs businessman Robert Blaha, El Paso County Com­mis­sion­er Darryl Glenn, and former Col­or­ado Small Busi­ness Ad­min­is­tra­tion dir­ect­or Greg Lopez. Two other candidates, Lar­imer County Sher­iff Justin Smith and state Sen­ate Ma­jor­ity Lead­er Mark Schef­fel, are also considering running. Smith had said he would probably not run if Brauchler did.

Brauchler’s pass piles on top of other problems standing in the Colorado GOP's way this year. This summer, state Republican Party chair Steve House accused other party leaders of attempting to oust him via a blackmail-based coup regarding an alleged extramarital affair. Among those accused were Coffman’s wife, state Attorney General Cynthia Coffman, who had also been considered a strong potential Bennet challenger. Coffman and the others denied any wrongdoing, but the episode once again exposed serious disagreements within a state party that had just been through a dramatic leadership shakeup that spring. 

This story has been updated with additional information.

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