Updated at 11:29 a.m. with Bivens’s statement.

Former Arizona Democratic Party chairman Don Bivens is dropping out of the state’s open Senate race, leaving former U.S. surgeon general Richard Carmona a clear Democratic primary.

“The continuing head-to-head competition of our Democratic primary is draining resources that we will need as a party to win the U.S. Senate race in November,” Bivens said in a statement. “While I am confident we would win this primary, the cost and impact on the party I’ve spent my life fighting for could diminish our chance to achieve the ultimate goal: winning in November.”

Bivens was the underdog in the primary, with much of the establishment lining up behind Carmona.

On the Republican side, Rep. Jeff Flake and businessman Wil Cardon are vying for their party’s nomination.

Sen. Jon Kyl (R-Ariz.) is retiring.