Key Senate Democrats swiftly urged McConnell not to hold a vote on confirmation until after the midterms. They cited the Kentucky Republican's decision to block then-President Barack Obama's nominee for the seat vacated by Justice Antonin Scalia's death until after the 2016 presidential election. The gambit paid off, as Trump won the presidency and nominated the conservative Gorsuch, who has already had a meaningful effect on the court's decisions .

Though Democrats face a daunting Senate electoral map, they have an outside chance of gaining enough seats to take a majority in the chamber. It would give them the ability to block President Donald Trump 's nominees to the top court and potentially force him to pick a more moderate justice. The GOP currently holds 51 of 100 seats in the chamber, and did away with the 60-vote precedent for Supreme Court judges in order to confirm Justice Neil Gorsuch last year.

Following Kennedy's announcement , Senate Majority Leader Mitch McConnell said the Senate "will vote to confirm Justice Kennedy's successor this fall." Senate Republicans plan to move quickly before November's midterm elections.

"Our Republican colleagues in the Senate should follow the rule they set in 2016 — not to consider a Supreme Court justice in an election year," Senate Minority Leader Chuck Schumer said Wednesday. "Senator McConnell would tell anyone who listened that the Senate had the right to advise and consent. And that was every bit as important as the president's right to nominate."

Sen. Dianne Feinstein, the top Democrat on the Senate Judiciary Committee, agreed with Schumer. The California Democrat said "there should be no consideration of a Supreme Court nominee until the American people have a chance to weigh in."

At least two other Judiciary Committee Democrats, Richard Blumenthal of Connecticut and Kamala Harris of California, said they concurred with their party's leader. The panel holds hearings for judges and decides whether to recommend them to the full Senate. Republicans have an 11-10 edge on the committee and can put judges through along party lines.

When asked Wednesday if he thinks it is fair to push for a confirmation before the midterms after his blockage of Garland, McConnell said, "There's no presidential election this year," according to NBC News.

Judiciary Committee Chairman Chuck Grassley, R-Iowa, also pointed to the fact that Obama appointed Justice Elena Kagan to the court during a midterm year in 2010. She was confirmed a few months before the elections.

Kennedy's departure gives Trump a chance to appoint another conservative to the court and shape U.S. policy for decades to come. His retirement could have huge effects on abortion rights and gay rights, including whether the court upholds Roe v. Wade.

The 81-year-old, who became a justice in 1988, was considered a swing vote on the court and joined with his liberal colleagues on some crucial decisions. His retirement is effective July 31.