President Barack Obama’s decision to nominate the moderately liberal federal appellate court Judge Merrick Garland to the U.S. Supreme Court had no immediate effect on Senate Republicans’ refusal to hold a hearing or allow a vote on filling the vacancy until after the presidential election.

Obama had lavish praise for Garland’s qualifications, experience and judicial philosophy in a half-hour Rose Garden ceremony on Wednesday morning and urged the U.S. Senate to act promptly on the nomination.

“I have fulfilled my constitutional duty,” Obama said, “and now it’s the Senate’s duty to fulfill theirs.”

But Senate Majority Leader Mitch McConnell took to the Senate floor within the hour to reaffirm that Republicans intend to leave the seat open for the next president.

“It is the president’s constitutional right to nominate a Supreme Court justice,” the Kentucky Republican said. “And it’s the Senate’s constitutional right to act as a check on the president and withhold its consent.”

Louisiana’s senior Republican senator David Vitter, a member of the Senate Judiciary Committee, also reaffirmed his support for deferring any action on the nomination until after the election. “President Obama has less than a year left, but a Supreme Court Justice will impact our country for decades,” Vitter said in a prepared statement.

Vitter’s Republican colleague Bill Cassidy also criticized the nomination.

“The president’s nominees have pushed our country to the left by supporting the president’s agenda,” Cassidy said in a statement. “I don’t support the president’s agenda. I don’t support the president’s nominees.”

The Supreme Court vacancy was created by the unexpected death of conservative Justice Antonin Scalia on Feb. 13. Scalia’s death at age 79 left the court evenly divided between a bloc of four conservatives, including the swing-vote moderate Anthony M. Kennedy, and four liberals.

Garland, 63, is chief judge of the U.S. Court of Appeals for the District of Columbia Circuit, which has outsized influence on regulatory issues because of its role in hearing challenges to federal agency decisions. President Bill Clinton nominated him for the court in 1995. After a delay, the Senate, then with a 55-45 Republican majority, confirmed him in 1997 by a vote of 76-23.

An honors graduate of Harvard College and Harvard Law School, Garland clerked for the highly regarded federal appeals court judge Henry Friendly and then for Supreme Court Justice William J. Brennan Jr. The Chicago native joined a high-powered Washington law firm, but left in 1989 to serve as an assistant U.S. attorney for the District of Columbia.

After a brief return to the firm, he left again in 1993 to join the Justice Department as deputy assistant attorney general for the criminal division. At the Justice Department, Garland oversaw the federal prosecutions of Timothy McVeigh for the Oklahoma City bombing and the so-called Unabomber Ted Kaczynski.

Garland has a reputation as a meticulous judge, with moderately liberal views on civil liberties and social issues and somewhat conservative stands on criminal law.

“Fidelity to the Constitution and the law has been the cornerstone of my professional life,” Garland said after Obama finished, “and it is the hallmark of the kind of judge I have tried to be over the last 18 years.”

Garland rose to the position of chief judge by seniority. With 19 years on the bench as of next Sunday, he has the most judicial experience of any Supreme Court nominee in history.

The White House created a new Twitter account, @scotusnom, to promote the nomination. Liberal and conservative groups already had started developing plans for public campaigns to support or oppose confirmation.

Obama said Garland would begin making courtesy calls on senators on Thursday. Senate Judiciary Committee Chairman Chuck Grassley, R-Iowa, has backed McConnell’s decision to hold no hearings on any Obama nomination, but he told the Des Moines Register on Wednesday that he would meet with Garland.

Several other Republican senators told news organizations they would meet with Garland. But many Capitol Hill observers were predicting Wednesday that Republicans would not yield to pressure to act on the nomination.

Kenneth Jost is a legal affairs journalist in Washington and author of Supreme Court Yearbook (CQ Press).