(Bloomberg) -- Republican Senator Susan Collins said she’d oppose Neera Tanden’s nomination for budget director, making an already fraught path to confirmation even more difficult.

“Congress has to be able to trust the OMB director to make countless decisions in an impartial manner, carrying out the letter of the law and congressional intent,” Collins, a moderate from Maine, said in a Monday morning statement. “Neera Tanden has neither the experience nor the temperament to lead this critical agency.”

President Joe Biden said Feb. 19 he would not withdraw Tanden’s nomination after Senator Joe Manchin, a West Virginia Democrat, announced he would vote against her. Manchin’s move means Tanden’s nomination would need the support of at least one Republican to be successful in the Senate, which is divided 50-50 along party lines.

Tanden, who has led the liberal think-tank Center for American Progress, faces strong Republican opposition over some of her sarcastic social media postings.

Collins cited Tanden’s posts as part of the reason for her opposition.

“Tanden’s decision to delete more than a thousand tweets in the days before her nomination was announced raises concerns about her commitment to transparency,” she said, adding, “Should Congress need to review documents or actions taken by OMB, we must have confidence that the Director will be forthcoming.”

Collins also said Tanden’s “past actions have demonstrated exactly the kind of animosity that President Biden has pledged to transcend.”

During her nomination hearing before the Senate Budget Committee, Tanden was chastised by Chairman Bernie Sanders for her past tweets and she pledged to refrain from making personal attacks -- such as those she had directed at Sanders in the past.

It wasn’t enough for Collins.

“I believe her overtly partisan statements will have a toxic and detrimental impact on the important working relationship between members of Congress and the next director of the Office of Management and Budget,” Collins said Monday.

If Tanden’s nomination fails, that could further delay the development of Biden’s fiscal 2022 federal budget proposal, which is already behind schedule and which is the first step in the funding process for the next fiscal year beginning Oct. 1. The OMB director is also in charge of promulgating regulations and acts as a liaison between the White House and federal agencies.

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