President Donald Trump’s determination to quickly pick a conservative successor to Supreme Court Justice Ruth Bader Ginsburg faced a challenge Saturday when a Republican senator said the winner of the November 3 election should choose her replacement.

One day after the liberal icon died, Republican senator Susan Collins said she would not support a vote on any Trump nominee before the election, in which polls show the president running behind Democratic rival Joe Biden.

Trump has the constitutional authority to nominate someone now, Collins acknowledged in a statement, and she said she would not object to the Senate Judiciary Committee opening hearings on his nominee.

However, she added, “In fairness to the American people, who will either be re-electing the president or selecting a new one, the decision on a lifetime appointment to the Supreme Court should be made by the president who is elected on November 3.”

That suggested that if the committee approved the nominee and sent him or her to the full Senate for final confirmation before the election, Collins could vote against the nominee.

Collins is the first Republican to take such a stance since Ginsburg died at 87 on Friday, after 27 years on the Supreme Court.

Ginsburg’s death gives Trump the opportunity to tilt the nine-justice Supreme Court bench solidly toward the right for decades to come with a 6-3 conservative majority.

He and Senate Majority Leader Mitch McConnell have firmly rejected Democrats’ calls for the process to be put on hold for the election.

The Republicans’ 53-47 majority in the Senate makes it likely that any nominee would pass with ease.

But Collins’ statement appears to narrow that margin, and several other Republicans have said in the past that they would oppose filling the seat so close to a national election.

McConnell showed he recognized that challenge Friday when he urged party members not to take a stance against a vote.

“Over the coming days, we are all going to come under tremendous pressure from the press to announce how we will handle the coming nomination,” he said in a letter to Republican senators.

“For those of you who are unsure how to answer, or for those inclined to oppose giving a nominee a vote, I urge you all to keep your powder dry.”

“This is not the time to prematurely lock yourselves into a position you may later regret,” he added.

Collins though is also facing a tough challenge for reelection in her state of Maine, and her support for some of President Trump’s more conservative policies, as well as his last Supreme Court nominee, appears to pushed voters toward her Democratic opponent.