The Senate voted to advance the nomination of Elbridge Colby to be undersecretary of defense for policy on Monday, teeing up a final confirmation vote for later this week, with three Democrats crossing party lines to vote in favor of advancing to a final vote on his confirmation.

Colby’s nomination advanced in a 53-39 vote on Monday evening, with no Republicans voting against him. It was unclear going into Monday’s vote what the final whip count would be, the result of Colby’s nomination being advanced in a secret vote during a classified session of the Senate Armed Services Committee last week. 

A final vote on Colby’s confirmation is scheduled for Tuesday morning. 

Sen. Jack Reed (D-RI), the top Democrat on Armed Services, Sen. Mark Kelly (D-AZ) and Sen. Elissa Slotkin (D-MI) voted for the procedural motion to advance Colby’s nomination to a final vote on Monday. All three serve on Armed Services, and Slotkin worked with Colby in the past. Slotkin, who has worked for the Defense Department and the Central Intelligence Agency, told Jewish Insider in February that she was familiar with Colby’s record because he “used to be my assistant.”

Sens. Ruben Gallego (D-AZ), Cory Booker (D-NJ), John Fetterman (D-PA), Kirsten Gillibrand (D-NY), Jon Ossoff (D-GA), Bernie Sanders (I-VT) and Tim Sheehy (R-MT) did not attend Monday’s vote. 

The Democratic backers of Colby come as something of a surprise given the tough questioning the nominee faced from Democrats at his confirmation hearing on his skepticism of U.S. support for Ukraine and other issues.

Colby has faced pushback from some Republican lawmakers over his past support for accommodating a nuclear Iran. He walked back some of those positions, including that the U.S. could contain a nuclear armed Iran and that it should not attack Iran to stop it from obtaining a nuclear weapon, during his confirmation hearing last month. 

Several Republicans could vote against Colby on the final vote on Tuesday, but none of the potential critics previewed their plans to JI on Monday.

Colby said at the hearing that a nuclear Iran would be an “existential danger” to the United States and that he would provide the administration with military options to prevent such an outcome. He also said his past comments had been intended to push back on what he viewed as an overly hawkish public consensus at the time.

Those comments, along with a private lobbying effort by Colby and his allies to assuage concerns and distance himself from other controversial Pentagon hires, had a positive impact on skeptical senators who had been hesitant about voting to confirm him. 

“Speaking for me, he did answer things the way he needed to answer them, adequate at least to my satisfaction,” one GOP senator told JI last month. “He has said the things he needed to say to the satisfaction of people who like me and maybe others — I can’t speak for any of them … and he was pretty convincing.”

Jewish Insider’s senior congressional correspondent Marc Rod contributed to this report.