Democratic presidential nominee Joe Biden urged Senate Republicans on Sunday to not confirm a new Supreme Court justice before the results of the election are known, saying doing so would cause “irreversible damage” to American democracy.

“To jam this nomination through the Senate is just an exercise in raw political power,” Biden said in an address from the National Constitution Center two days after the death of Associate Justice Ruth Bader Ginsburg. “And I don’t believe the people of this nation will stand for it.”

Speaking directly to a small number of Republicans who could block a nomination by President Donald Trump in the Senate, Biden said: “Don’t vote to confirm anyone nominated under the circumstances President Trump and Sen. McConnell have created. Don’t go there. Uphold your constitutional duty — your conscience. Cool the flames that have been engulfing our country.

“The last thing we need is to add a constitutional crisis that plunges us deeper into the abyss, deeper into the darkness,” Biden added. “If we go down this path, it would cause irreversible damage. The infection this president has unleashed on our democracy can be fatal. Enough."

The sudden political fight over filling Ginsburg’s seat is a new defining issue in an already combustible presidential election roiled by a year of national crises. Both Democrats and Republicans in Pennsylvania said over the weekend that it will inspire their voters to turn out in force.

Democrats have expressed outrage, though not surprise, at a pledge made immediately after Ginsburg’s death by Mitch McConnell, the Republican majority leader, that the Senate will vote on Trump’s nominee.

That marked a reversal from four years ago, when McConnell refused to allow a vote on President Barack Obama’s Supreme Court pick, saying Americans should first make their voices heard in an election that was eight months away — far more than the 43 days left now.

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On Sunday, Biden cited Ginsburg’s “dying words” — spoken days before her death and relayed by her family — that she not be replaced “until a new president is installed.”

“As a nation, we should heed her final call to us not as a personal service to her, but as a service to our country at a crossroads,” Biden said.

Biden spoke at length about a Trump administration case before the Supreme Court seeking to overturn the Affordable Care Act’s protections for people with preexisting medical conditions. He noted that survivors of the coronavirus suffer lung scarring and other lingering effects, trying to keep the focus on two issues Democrats believe can help them beat Trump: the pandemic and health care.

He cited “nearly half a century of legal precedent" protecting abortion rights, starting with the 1973 Supreme Court decision in Roe v. Wade. .

“There’s so much at stake," Biden said, noting other cases before the court. "The right to health care, clean air, clean water, the environment, equal pay for equal work, the rights of voters, immigrants, women, workers. And right now, our country faces a choice, a choice about whether we will come back from the brink.”

And he pointed to McConnell’s refusal to consider Obama’s 2016 nomination of Judge Merrick Garland.

“Having made this their standard when it served their interests, they cannot, just four years later, change course when it doesn’t serve their ends,” Biden said. Conceding that he wouldn’t persuade Trump or McConnell, Biden added: “I’m speaking to those Senate Republicans who know deep down what is right for the country and consistent with the Constitution.”

» READ MORE: ‘Disgusted’ voters in the Philly suburbs could help Biden offset Trump’s gains in Pennsylvania

Trump, speaking at the White House on Saturday, vowed to press forward with a nomination. He said he has a list of about 45 potential picks and expects to select a woman.

“There’s been many occasions where, frankly, it turned out to be during a presidential year,” Trump said. “But we want to respect the process, and the process will move. I think it’s going to move very quickly, actually.”

And Trump pushed back against Sen. Susan Collins, a Maine Republican in a difficult reelection battle, who said the winner of the November election should fill the seat.

“We won,” Trump said of the 2016 election. “And we have an obligation, as the winners, to pick who we want.”

Sen. Lisa Murkowski, an Alaska Republican, on Sunday became the second member of the GOP conference to say the election’s winner should make the selection. With a narrow majority, Republicans can only afford to lose one more senator on a Supreme Court vote, which would lead Vice President Mike Pence to cast the tie-breaking vote.

» READ MORE: Pat Toomey took a stance on Obama’s last Supreme Court nominee. He’ll face pressure to stick to it now.

Sen. Pat Toomey, the Pennsylvania Republican who joined McConnell in blocking Garland’s nomination in 2016, hasn’t taken a position on confirming a new justice. Trump and McConnell haven’t made clear whether they will move to do so before the election or during a lame duck session after.

Republicans are particularly hopeful that the court fight will energize conservative voters, who have a history of rallying around judicial issues. The court seat Republicans held open in 2016 was a key motivator for some of those voters in backing Trump, exit polls showed. Trump’s campaign flooded supporters with emails and text messages over the weekend, offering “fill that seat” T-shirts in exchange for $30 contributions.

Trump has consistently trailed Biden in national polls and in surveys of critical swing states like Pennsylvania, and the race has been remarkably stable even in the face of a pandemic, a recession, and a national reckoning over systemic racism. An NBC News/Wall Street Journal national poll released Sunday showed Biden beating Trump by 8 points — identical to his margin in the same poll in February.

Democrats had their own reasons to be optimistic about political energy on their side. Donors gave Democratic candidates $70.6 million on Saturday through the party’s main online fund-raising website, ActBlue, shattering a previous record.

» READ MORE: Ruth Bader Ginsburg lauded in Philly as a legal and feminist icon ‘whose voice soared above the rest’

In his remarks Sunday, Biden reiterated his campaign promise to nominate a Black woman to the court for the first time. But he was critical of Trump for releasing names of potential nominees, saying it could influence their rulings or create the perception of influence if they hold lower court seats. Biden said he wouldn’t do the same because it would make his potential nominees “subject to unrelenting political attacks.”

“I’ll consult with senators in both parties about that pick, as well as legal and civic leaders in our country,” Biden said. “In the end, the choice will be mine and mine alone, but I will consult.”

He noted several times that millions of voters will have already cast their ballot for president by Oct. 1, amid a historic increase in early voting and voting by mail because of the pandemic.

“And you can’t un-ring the bell,” Biden said. “In just a few weeks, all voters in this nation will be heard. They’re the ones that the Constitution envisions should decide who has the power to make this appointment.”