WASHINGTON (AP) — The extraordinary effort to overturn the presidential election is ripping the Republican Party apart as GOP lawmakers orchestrating the challenges to Joe Biden's victory faced intense blowback Sunday from others in the party warning they are undermining Americans' faith in democracy.

President Donald Trump has enlisted support from a dozen Republican senators and up to 100 House Republicans to challenge the Electoral College vote when Congress convenes in a joint session to confirm President-elect Joe Biden’s 306-232 win.

With Biden set to be inaugurated Jan. 20, the outgoing president is intensifying efforts to prevent the traditional transfer of power. Trump can be heard in an audio recording pressuring Georgia's election officials to “find” enough votes to flip Biden's win to him. Allies are pressuring Vice President Mike Pence to ensure Trump's victory in presiding over the congressional session. Trump is whipping up crowds for a rally in Washington.

But without evidence of voter fraud or other problems, leading Republicans across the nation are joining Democrats in saying there is no reason for the federal government to intervene in what state officials have certified were free and fair elections. Attorney General William Barr, who was appointed by Trump, said before leaving office that there was no evidence of fraud that would change the election outcome.

“The 2020 election is over,” said a statement Sunday from a bipartisan group of 10 senators, including Republicans Susan Collins of Maine, Lisa Murkowski of Alaska, Bill Cassidy of Louisiana and Mitt Romney of Utah.

“At this point, further attempts to cast doubt on the legitimacy of the 2020 Presidential election are contrary to the clearly expressed will of the American people and only serve to undermine Americans’ confidence in the already determined election results,” the senators wrote.

Republican Gov. Larry Hogan of Maryland said, “The scheme by members of Congress to reject the certification of the presidential election makes a mockery of our system and who we are as Americans.”

The unusual challenge to the presidential election, on a scale unseen since the aftermath of the Civil War, clouded the opening of the new Congress and is set to consume its first days. The House and Senate will meet Wednesday in a joint session to accept the Electoral College vote, a typically routine process that's now expected to be a prolonged fight.

Biden’s transition spokesman, Mike Gwin, dismissed the effort as a “stunt” that won’t change the fact that Biden will be sworn in Jan. 20.

The effort being led by Sen. Josh Hawley, R-Mo., and Sen. Ted Cruz, R-Texas, was hit with swift criticism.

Sen. Lindsey Graham, R-S.C., said Sunday his colleagues will have an opportunity to make their case, but they must produce evidence and facts. “They have a high bar to clear," he said.

Others simply said they do not plan to join the effort. “I don’t think either of the two efforts has any chance for success,” said Missouri's other senator, Republican Roy Blunt.

House Speaker Nancy Pelosi said in a letter to colleagues that while there is “no doubt as to the outcome of the Biden-Harris presidency, our further success is to convince more of the American people to trust in our democratic system.”

Hawley defended his actions in a lengthy email to colleagues, explaining that his Missouri constituents have been “loud and clear” with their belief that Biden's defeat of Trump was unfair.

“It is my responsibility as a senator to raise their concerns,” Hawley wrote late Saturday.

Hawley plans to object to the state tally from Pennsylvania. But that state's Republican senator, Pat Toomey, criticized the attack on Pennsylvania's election system and said the results that named Biden the winner are valid.

Cruz's coalition of 11 Republican senators vows to reject the Electoral College tallies unless Congress launches a commission to immediately conduct an audit of the election results. They are zeroing in on the states where Trump has raised unfounded claims of voter fraud. Congress is unlikely to agree to their demand.

The group formed with Cruz, which presented no new evidence of election problems, includes Sens. Ron Johnson of Wisconsin, James Lankford of Oklahoma, Steve Daines of Montana, John Kennedy of Louisiana, Marsha Blackburn of Tennessee and Mike Braun of Indiana. Also part of the effort are some of the new senators: Cynthia Lummis of Wyoming, Roger Marshall of Kansas, Bill Hagerty of Tennessee and Tommy Tuberville of Alabama.

The convening of the joint session to count the Electoral College votes has faced objections before. In 2017, several House Democrats challenged Trump’s win but Biden, who presided at the time as the vice president, swiftly dismissed them to assert Trump's victory. Rarely have the protests approached this level of intensity.

The moment is a defining one for the Republican Party in a post-Trump era. Both Hawley and Cruz are potential 2024 presidential contenders, cementing their alignment with Trump’s base of supporters. Others are trying to forge a different path for the GOP.

Pence will be carefully watched as he presides over what is expected to be a prolonged showdown, depending on how many challenges are mounted.

The vice president “welcomes the efforts of members of the House and Senate to use the authority they have under the law to raise objections,” Pence's chief of staff, Marc Short, said in a statement Saturday.

Senate Majority Leader Mitch McConnell has warned Republicans off such challenges but said little when asked about it as at the Capitol as the Senate opened Sunday.

“We’ll be dealing with all of that on Wednesday,” he said.

Congress have been loathe to interfere in the state-run election systems, a longstanding protocol. States choose their own election officials and draft their election laws. During the coronavirus pandemic many states adapted by allowing mail voting to ease health risks of voting in person. Those changes and others are now being challenged by Trump and his allies.

Trump, the first president to lose a reelection bid in almost 30 years, has attributed his defeat to widespread voter fraud, despite the consensus of nonpartisan election officials and even Trump's attorney general that there was none. Of the roughly 50 lawsuits the president and his allies have filed challenging election results, nearly all have been dismissed or dropped. He’s also lost twice at the U.S. Supreme Court.

The 5th U.S. Circuit Court of Appeals rejected the latest challenge from Rep. Louie Gohmert, R-Texas, and a group of Arizona electors, who filed suit to try to force Pence to step outside mere ceremony and shape the outcome of the vote. The appellate court sided with the federal judge, a Trump appointee, who dismissed the suit.