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Senate Majority Leader Mitch McConnell dismissed a pledge from his Democratic counterpart to block President-elect Donald Trump’s Supreme Court nominee, insisting “the American people simply will not tolerate” such a move.

McConnell’s comments come the day after Senate Minority Leader Chuck Schumer told MSNBC’s Rachel Maddow on Tuesday that “if [Republicans] don't appoint somebody good, we're going to oppose them tooth and nail,” in part as retaliation for Senate Republicans' refusal to consider President Barack Obama's nomination of U.S. Appeals Judge Merrick Garland to the court.

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Speaking to reporters on Capitol Hill, McConnell wryly called Schumer’s comment an “expansion” of the so-called “Biden rule,” a reference to comments then-Sen. Joe Biden made in 1992 arguing against holding confirmation hearings for a Supreme Court nominee during an election year. The Kentucky Republican has held up the Vice President’s comments to defend Senate Republicans’ refusal to consider Garland’s nomination.

“Apparently there’s yet a new standard now, which is to not confirm a Supreme Court nominee at all,” McConnell said, adding: “I think that’s something the American people simply will not tolerate, and we’ll be looking forward to receiving a Supreme Court nomination and moving forward on it.”

The exchange hints at the rancor already brewing over the Supreme Court pick and over Trump’s Cabinet nominations more broadly, which are just a few of the many clashes shaping up between the two parties on Capitol Hill as Republicans take full control of Washington this month.

On Wednesday, President Obama visited Capitol Hill to huddle with Democrats about their strategy for blocking GOP attempts to dismantle his signature legislative achievement, the Affordable Care Act.

But Schumer’s comments on MSNBC Tuesday night hinted at just how hard Democrats will hold the line on the Supreme Court nomination — even though Democrats used Republicans’ refusal to consider a nominee against the GOP during the 2016 elections.

He suggested no conceivable Trump Supreme Court pick could pass muster for Democrats: "It's hard for me to imagine a nominee that Donald Trump would choose that would get Republican support that we [Democrats] could support,” Schumer said.