Maine Republican Sen. Susan Collins says the nomination of a Supreme Court justice to fill the vacancy left by the death of Ruth Bader Ginsburg should be made by whichever candidate wins the presidential election.

With Republican leadership united behind President Trump's decision to quickly nominate a new Supreme Court justice to fill the vacancy left by Ruth Bader Ginsburg's death Friday, Senate Democrats are hoping to block a vote by swaying a few moderate Republicans to their side.

Judges Amy Coney Barrett, Barbara Lagoa and Amul Thapar are being seriously considered by President Trump for nomination to fill the seat on the Supreme Court vacated by the death of Justice Ruth Bader Ginsburg, according to sources familiar with the process.

An announcement on the nominee could come as early as Monday or Tuesday.

Updated at 3:09 p.m. ET

Almost immediately upon learning of the death of Supreme Court Justice Ruth Bader Ginsburg, attention moved to whether Republicans would attempt to fill her seat before the election.

Many eyes turned to moderate Republican senators like Susan Collins of Maine or Lisa Murkowski of Alaska. But even more conservative Republicans have, in the past, expressed their reluctance to fill a vacancy during an election year. Chief among those is South Carolina Sen. Lindsey Graham.

Democratic vice presidential nominee Kamala Harris and her husband, Doug Emhoff, stopped outside the Supreme Court Saturday morning, following the death of Supreme Court Justice Ruth Bader Ginsburg.

"Justice Ginsburg was a titan—a relentless defender of justice and a legal mind for the ages," Harris said in a tweet. "The stakes of this election couldn't be higher. Millions of Americans are counting on us to win and protect the Supreme Court—for their health, for their families, and for their rights."

When President Trump learned Friday night that Justice Ruth Bader Ginsburg had died, he told reporters she was an "amazing woman." Later, in an official statement, he called her a "titan of the law." And while Senate Majority Leader Mitch McConnell, R-Ky., wrote in a statement that he would bring a vote for a new justice to the floor, Trump did not weigh in.

Candidates on the short list for a Supreme Court vacancy undergo intense vetting that typically culminates in a one-on-one interview with the president.

The process is shrouded in secrecy, but President Trump's flair for the dramatic has introduced a sense of showmanship to the highly choreographed rollout.

In politics, money can be a pretty good stand-in for enthusiasm. And the donations pouring in to the Democratic fundraising platform ActBlue since Ruth Bader Ginsburg's death indicate there is a lot of energy and money on the left.

According to the constantly-ticking tracker on ActBlue's website, in the hours from 9 p.m. ET, when the news of Ginsburg's death became widely known, to Saturday afternoon, more than $46 million was donated to Democratic candidates and causes. The number keeps rising by thousands every second.

President Trump, who called Justice Ruth Bader Ginsburg "a titan of the law," will be able to pick a successor for her from a list of nearly four dozen names that he updated Sept. 9.