Republicans indicated they would try to block one of Joe Biden's proposed key economic advisers in what could be the first major confirmation battle of his administration.
Mr Biden on Monday nominated Neera Tanden, 50, as the first woman of colour to be director of the Office of Management and Budget.
Ms Tanden has for the last decade headed a liberal think tank, and is a former close aide to Hillary Clinton.
She has been a vocal critic of Republican senators including leader Mitch McConnell, accusing him of "breaking our democracy".
A spokesman for Republican senator John Cornyn accused her of "an endless stream of disparaging comments," and said she "stands zero chance of being confirmed". Mr McConnell's former chief of staff said Ms Tanden would be a "sacrifice to the confirmation gods".
It came as Mr Biden received the Presidential Daily Brief for the first time, giving him an update on classified intelligence.
That would be expected to include the latest US intelligence assessments of the assassination of Iranian nuclear scientist Mohsen Fakhrizadeh.
The president-elect also revealed his economic team, including confirmation that he was nominating Janet Yellen, the former Federal Reserve chair, as treasury secretary.
He also named an all-female senior White House communications team with Jen Psaki as press secretary.
Ms Psaki worked in Barack Obama's administration, and has been a contributor to CNN.
The confirmation of Ms Tanden looked set to depend on who wins two Senate run-off races in Georgia on January 5.
If Democrats win both races they will take control of the Senate from Republicans, easing the confirmation process for Biden officials.
As the battle in Georgia heated up its secretary of state Brad Raffensperger opened investigations into left-wing groups trying to sign up new voters.
He said some groups had been encouraging people who lived outside Georgia to register to vote in the state.
Ms Tanden is also unpopular with some on the left wing of the Democratic party.
Last year Bernie Sanders accused her of "maligning my staff and supporters and belittling progressive ideas".