Ms. Tanden, who was a senior adviser to Hillary Clinton’s 2016 presidential campaign, had drawn bipartisan criticism for a prolific stream of vitriolic social media posts that lambasted lawmakers in both parties and for her work at a liberal think tank. Mr. Biden selected her to direct the Office of Management and Budget before Democrats had won control of the Senate, surprising lawmakers and aides in both parties.
During Ms. Tanden’s confirmation hearings, senators grilled her about her social media posts and her decision to delete more than 1,000 Twitter comments before appearing on Capitol Hill. She apologized for the online venom, but it was clear that some senators were not inclined to disregard it.
Having clashed with Senator Bernie Sanders, the Vermont independent who chairs the Budget Committee, and other progressives, Ms. Tanden also faced scrutiny for her comments attacking progressives and for corporate donations she had secured while she was in charge of the Center for American Progress.
In the past 10 days, her nomination had teetered on the brink of collapse as centrist Democrats and Republicans — first Senator Joe Manchin III, Democrat of West Virginia, then Senators Mitt Romney of Utah and Susan Collins of Maine, both Republicans — announced they would not back her. That imperiled Ms. Tanden’s margin for confirmation in the 50-50 Senate, leading two committees to abruptly postpone votes last week on advancing her nomination.
With at least one Republican needed to join all the Democrats, Republican leaders privately counseled their senators to remain united in opposition to Ms. Tanden. Senator Lisa Murkowski of Alaska, a moderate Republican who was thought to be a potential supporter, had not publicly announced her position, but it was not clear that there would be enough Democrats behind Ms. Tanden to confirm her even if she had won Ms. Murkowski’s backing. The two met on Capitol Hill on Monday.