In a statement outlining his decision, Manchin said, “I met with Justice Jackson and assessed her qualifications to be a Supreme Court judge. After meeting with her, reviewing her case and closely following her testimony and questioning before the Senate Judiciary Committee this week, I determined that I intended to vote for his Supreme Court nomination.”

Manchin’s announcement is notable because he is a closely watched moderate Democrat and a key vote in the Senate. His decision to vote “yes” helps solidify the vote count for Senate Democrats to confirm the nominee.

Senate Democrats hope to move quickly to a confirmation vote by the full Senate early next month. They can confirm Jackson to the Supreme Court without Republican support if every member of their caucus votes yes, which looks set to happen, and Vice President Kamala Harris breaks the tie. It is not yet clear if Jackson will win any Republican votes.

Senate Majority Leader Chuck Schumer promised in a floor speech Thursday to bring the nomination to the Senate “at short notice” once the Senate Judiciary Committee advances the nomination. The Judiciary Committee is expected to vote on the nomination on April 4.

Jackson appeared before the committee for high-profile confirmation hearings this week, which included intense questioning by Senate Republicans.

So far, no Democrat has publicly signaled they would vote against the nominee, even as Republicans have worked to unleash potentially politically damaging attacks, such as accusations that Jackson is soft on crime, a charge the candidate and many Democrats have pushed back against.

While Republicans attacked the candidate’s record this week, Democrats praised her credentials and experience, describing her as exceptionally qualified. Democrats have also consistently stressed the historic nature of Jackson’s nomination. If confirmed, Jackson would be the first black woman to serve on the Supreme Court.

When the Senate voted to confirm Jackson last year to fill a vacancy on a powerful DC-based appeals court, three Republican senators voted with the Democrats in favor: the senses. Lindsey Graham from South Carolina, Susan Collins from Maine and Lisa Murkowski from Alaska. As a result, these three Republicans have been closely watched this week.

Collins and Murkowski are not on the Senate Judiciary Committee, so they did not have the opportunity to question the nominee during the hearings.

But Graham is a member of the panel. The Republican from South Carolina has addressed some fierce and highly critical questions to the nominee as he appears to be signaling that he will not support her nomination.

Graham told CNN earlier this week that it’s “fair to say” he sees red flags with the nomination.

And Republican Sen. Ben Sasse of Nebraska, who was one of Jackson’s most respectful Republicans, said Friday night he would vote against confirmation, meaning the Senate Judiciary Committee may find itself in the dark. stalemate 11-11. The nomination would still advance to the floor if there was a tie vote.

This story has been updated with additional details and reaction.

CNN’s Manu Raju contributed to this report.