Democrats are launching a "full-scale effort" to drum up the votes to confirm Neera Tanden, President Biden's pick to be the director of the Office of Management and Budget, after powerful moderates in the Senate signaled they wouldn’t offer their support. 

Asked if he would whip the Tanden confirmation vote, Sen. Majority Whip Richard Durbin, D-Ill., said: "We're doing a kind of a full-scale effort, including the White House and others to find support."

White House press secretary Jen Psaki refused to say whether Biden was considering an alternative to the embattled OMB nominee. "There is one candidate to lead the budget department. Her name is Neera Tanden," she said. 

Psaki said Wednesday that both the White House and Tanden were in the "fighting" phase and were "doing outreach" to senators to find support. 

"It's a numbers game, right? It's a matter of getting one Republican to support her nomination," she said. 

NEERA TANDEN COMMITTEE VOTES ABRUPTLY DELAYED 

The feisty longtime Democratic policy advisor lost support from Sen. Joe Manchin, D-W.Va., due to her Twitter fingers, which he said foreshadowed a "toxic and detrimental" relationship between the OMB and Congress. 

Without Manchin’s vote, Tanden would be down to support from only 49 Democrat senators. But another moderate Democrat, Sen. Kyrsten Sinema, Ariz., has not said how she’ll vote, and neither has Bernie Sanders, Vermont, a punching bag for Tanden when she worked on Hillary Clinton’s campaign in 2016. Sanders confronted Tanden during a Budget Committee vote over corporate donations to the Center for American Progress while she was president and for "vicious attacks" on progressives such as himself. 

Sen. Susan Collins, R-Maine, who has not yet opposed a single Biden nominee, said she would not be voting to confirm Tanden on Monday. Tanden once referred to Collins as "the worst" in a tweet. Sens. Shelley Capito, R-W.Va., Rob Portman, Ohio, and Mitt Romney, R-Utah, who also have not yet opposed a Biden nominee, all said that they will oppose Tanden. 

No other Republican has come forward to support her nomination. Tanden could attempt to find a friend in Sen. Lisa Murkowski, R-Alaska, who told reporters she is "still visiting" the matter. 

The Senate Homeland Security and Governmental Affairs Committee (HSGAC) and Budget Committees postponed planned business meetings Wednesday where they were supposed to vote on Tanden, throwing her confirmation further into doubt by the cancellation of the two committee votes. 

In a previous confirmation hearing, Tanden faced fire for hostile remarks of both Republicans and progressives. 

BIDEN'S OMB PICK NEERA TANDEN ANGERS BERNIE SANDERS-ALLIED PROGRESSIVES

Portman gave examples of "a few of the thousands of negative public statements" Tanden has made. These included her calling Sen. Tom Cotton, R-Ark., a "fraud," saying that "vampires have more heart than Ted Cruz," and referring to then-Senate Majority Leader Mitch McConnell, R-Ky., as "Moscow Mitch" and "Voldemort," referring to the Harry Potter villain.

Portman said that even after Tanden deleted tweets, there were still nine pages of posts about Cruz that were still up.

"I wonder, specifically, how do you plan to mend fences and build relationships with members of Congress you have attacked through your public statements?" Portman asked.

"I recognize the concern," Tanden replied. "I deeply regret and apologize for my language — some of my past language. I recognize that this role is a bipartisan role, and I know I have to earn the trust of senators across the board. I will work very aggressively to meet that concern."

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Tanden said she hopes to work "in a bipartisan and nonpartisan manner," while acknowledging that "it’s upon me to prove that to this committee and to members."

Fox News' Ronn Blitzer contributed to this report.