WASHINGTON — Senator Dianne Feinstein, Democrat of California, was returning to Washington on Tuesday evening, her office announced, after a nearly three-month absence from the Senate that threatened to deprive her party of the ability to advance President Biden’s judicial nominees and grind its agenda to a halt in the closely divided chamber.

It was not clear if Ms. Feinstein, 89, would make it back in time for a vote scheduled for Tuesday night, a spokesman said. But her return to the chamber would restore a Democratic majority to the Judiciary Committee, where Democrats were becoming increasingly concerned about their limited ability to move forward with judicial nominations.

Ms. Feinstein, who was hospitalized in February for shingles, for weeks gave no detailed updates about her health as she recovered in San Francisco, and provided no timeline for her planned return to the Senate. Her prolonged absence left her colleagues in the Senate fearing that they would be short a vote not only on the Judiciary Committee but also on other crucial matters.

“The bottom line is the business of the committee and the Senate is affected by her absence,” Senator Richard J. Durbin, Democrat of Illinois and chairman of the Judiciary Committee, said Sunday on CNN’s “State of the Union.”

Other Democrats, like Representatives Ro Khanna of California and Alexandria Ocasio-Cortez of New York, called for Ms. Feinstein to resign, publicly questioning whether she was able to perform her job. And a coalition of 65 grass-roots organizations in California signed a letter requesting that she step down and allow Gov. Gavin Newsom of California “to appoint an interim senator who can provide robust and constant representation for California through the election of 2024.”

Ms. Feinstein, however, fired back, saying in a statement that there had been “no slowdown” of judicial confirmations during her absence and that she planned to return and finish out her term. Earlier this year, she announced she would not seek re-election in 2024.