In a blow to former Arizona Democratic Party Chairman Don Bivens’ campaign for the Senate, former Rep. Ann Kirkpatrick (D) has withdrawn her primary endorsement of him.

“Ann has decided to be neutral in the Senate primary, but she looks forward to seeing an Arizona Democrat win that seat in the general election,” Kirkpatrick spokeswoman Jennifer Johnson said in a statement.

“Ann has expressed that she wants to focus on her own race,” Bivens spokesman Mark Bergman said. “Don looks forward to running with her on the ticket this November.”

Kirkpatrick is locked in a tough battle to recapture the 1st district.

Bivens had a strong start with a burst of fundraising during his third-quarter entrance into the race. But the addition of former Surgeon General Richard Carmona to the Democratic primary has changed the game.

Kirkpatrick endorsed Bivens on Nov. 8, two days before Carmona’s unofficial entrance into the race.

Kirkpatrick’s change of heart hurts Bivens’ campaign in that, early on, she gave credence to the narrative that state Democrats backed their former party chairman, while national Democrats — including President Barack Obama — were pushing the Carmona campaign.

The Bivens campaign maintains he has wide support throughout the state, including the backing of 12 current and former state legislators.

Regardless, whoever wins the Democratic nod will have a tough road to the Senate. Roll Call Politics rates this race as Likely Republican.