Almost immediately after the first public confirmation that Justice Antonin Scalia had died, Senate Majority Leader Mitch McConnell signaled that the GOP-controlled Senate would block President Obama from nominating Scalia’s successor.

“The American people‎ should have a voice in the selection of their next Supreme Court Justice,” McConnell said in a statement. “Therefore, this vacancy should not be filled until we have a new President.”

McConnell’s statement came as a chorus of conservatives called for the confirmation process to be delayed until the next President takes office in January 2017. Not longer after, Sen. Chuck Grassley — the chair of the Senate Judiciary Committee, through which Supreme Court nominations come through — also issued a statement that said “it only makes sense” to wait until the next president is elected to replace Scalia.

Minority Leader Harry Reid countered in his own statement Saturday that said the “Senate has a responsibility to fill vacancies as soon as possible.”

“It would be unprecedented in recent history for the Supreme Court to go a year with a vacant seat,” Reid said. “Failing to fill this vacancy would be a shameful abdication of one of the Senate’s most essential Constitutional responsibilities.”

The move would deny President Obama the opportunity to name his third Supreme Court justice and potentially to change the court dramatically from a conservative to liberal majority.

The possibility of a Republican Senate thwarting a Supreme Court nomination for the remainder of Obama’s presidency sets the stage for a major political battle running parallel with the 2016 elections.

Sen. Ted Cruz (R-TX), a presidential candidate, was among the first to call for a delay.

Justice Scalia was an American hero. We owe it to him, & the Nation, for the Senate to ensure that the next President names his replacement. — Ted Cruz (@tedcruz) February 13, 2016

Saddened by Justice Scalia’s passing. The next President must nominate successor that upholds constitution, founding principles. — Tim Scott (@SenatorTimScott) February 13, 2016

But given the post-legal nature of this President I want McConnell to make a full year commitment to block noms till 2017. — Amanda Carpenter (@amandacarpenter) February 13, 2016

Sen. Patrick Leahy (D-VT), the top Democrat on the Senate Judiciary Committee, which would consider the nomination of Scalia’s successor, quickly sought to head off talk of delay.

“I hope that no one will use this sad news to suggest that the President or the Senate should not perform its constitutional duty,” Leahy said. “The American people deserve to have a fully functioning Supreme Court. The Supreme Court of the United States is too important to our democracy for it to be understaffed for partisan reasons. It is only February. The President and the Senate should get to work without delay to nominate, consider and confirm the next justice to serve on the Supreme Court.”

With only eight justices this year, the court could be split 4-4 on the series of high-profile, polarizing decisions. If the Senate does refuse to approve anyone Obama nominates, the court could be without a ninth justice until sometime in 2017.