Sen. Steve Daines, R-Mont., will introduce a resolution condemning packing the Supreme Court -- as Republicans increase their opposition to calls by a number of Democrats to adopt the policy of upping the number of justices on the court.

"This absolutely undermines the separation of powers that our Founding Fathers envisioned," Daines said at a press conference with Senate Republicans on Wednesday. "We have a 150-year precedent in this country of protecting the Supreme Court with nine justices."

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"Our Founding Fathers would roll over in their graves if they saw what's happening and being discussed right now by [Senate Minority Leader] Chuck Schumer and the Democrats," he said.

A draft of the resolution calls for the Senate to oppose “any attempt to increase the number of justices of the Supreme Court of the United States or otherwise pack the court,” arguing that it would “undermine the democratic institutions and destroy the credibility of the highest court in the United States."

At the press conference, Daines said packing the court would also be an "attack on the Montana way of life" and pointed to recent rulings at home from "liberal activist judges."

"It was a liberal judge that stopped the Keystone pipeline. It's liberal judges that stopped timber projects, they don't allow our loggers to be in our forests thinning them to prevent catastrophic wildfires," he said.

Adding justices on the Supreme Court was attempted unsuccessfully by President Franklin Delano Roosevelt in 1937 to force through parts of his New Deal that were ruled unconstitutional by the high court, and has been a fringe idea for years. 

The notion, however, has gained traction on the left since Republicans refused to hold hearings for President Barack Obama's nominee Merrick Garland in 2016. A number of Democrats in the presidential primary backed court packing, although now-Democratic nominee Joe Biden rejected the idea at the time.

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It has been given a fresh boost of energy on the left since the nomination of Amy Coney Barrett to the Supreme Court. Democrats have accused Republicans of ramming through the nomination too close to Election Day, and of doing their own version of “packing” the court.

Daines’ Senate opponent, Gov. Steve Bullock, said in a recent debate that if Barrett was confirmed, he would be open to measures including adding justices to the bench.

“We need to figure out the ways to actually get the politics out of the court,” Bullock said. “That’s anything from a judicial standards commission, or we’ll look at any other thing that might be suggested, including adding justices.”

But polls suggest voters do not like the idea. A New York Times/Siena poll found that 58% of likely voters said Democrats should not increase the size of the court, and just 31 percent in favor.

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Democratic presidential nominee Joe Biden has been evasive on the question. Last week he said he will “make clear” his position on adding justices to the Supreme Court when the Senate votes on the nomination of Amy Coney Barrett.

“I'm going to make clear my position in the next several days when they vote on this nominee, but I’ve got to keep the focus on that,” he said in an interview with Fox 2 Detroit.

Daines' resolution notes prior comments by then-Sen. Biden who has called court packing attempts by Roosevelt “a bonehead idea” and a “terrible, terrible mistake.” It also noted late Justice Ruth Bader Ginsburg’s comments in 2019 in which she called Roosevelt’s court packing push a “bad idea” and one that would “make the court look partisan.”

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Daines' resolution is one of a number of moves by Republicans that will look to put pressure on Democrats to get on the record on where they stand.

A number of Republican senators, including Sens. Marco Rubio of Florida and Ted Cruz of Texas, have laid out a proposal for a constitutional amendment to keep the number of justices at nine. Daines spoke alongside them and a number of other Republicans promoting the measure on Wednesday afternoon.

Barrett’s confirmation is expected to be advanced by the Senate Judiciary Committee in the coming days and be voted on in the full Senate before the end of the month.

The Associated Press contributed to this report.