“Most of my Republican colleagues in the House, and countless millions of our constituents across the country, now have serious concerns with the integrity of our election system. The purpose of our amicus brief will be to articulate this concern and express our sincere belief that the great importance of this issue merits a full and careful consideration by the Court,” U.S. Rep. Mike Johnson, who led the effort to draft an amicus brief in the case, said in a statement to Newsweek.

Johnson, vice chairman of the House Republican Conference in the upcoming term and currently chairman of the influential Republican Study Committee, has been a strong ally of Trump—even serving on his impeachment defense team and counseling Trump’s lawyers behind-the-scenes ahead of Trump’s Senate acquittal in February.

A spokeswoman told Newsweek on Thursday that Johnson was in meetings and traveling so he was unable to speak by phone.

More than half of the House Republican caucus signed onto Johnson’s brief after Trump urged Johnson to drum up signatures. Johnson sent an email noting he would be sending a list to Trump of those who sign on after the two shared a phone call Wednesday morning. Trump has been on Twitter and in private conversations attacking prominent Republicans who haven’t backed his efforts to overturn the election results, including Georgia’s governor, lieutenant governor and secretary of state.

House Minority Whip Steve Scalise, also a Louisiana Republican, and Rep. Jim Jordan, the Ohio Republican who is the ranking member on the Judiciary Committee, were among the amicus brief signees.

The brief backs a lawsuit brought by Texas Attorney General Ken Paxton, a close Trump ally who the Associated Press reports is being investigated by the FBI. Since Paxton filed the suit, 17 states with Republican attorneys general have also joined—winning Trump’s praise.

The states behind the suit claim that their votes are “diluted by the illegal and unconstitutional conduct” in the four states where the votes are being challenged—Georgia, Pennsylvania, Michigan and Wisconsin. It doesn’t provide evidence of illegal conduct, instead suggesting that “it is only necessary to demonstrate that the elections in the defendant States materially deviated from the ‘manner’ of choosing electors established by their respective state Legislatures.”

The members of Congress argue in their amicus brief that states changed their voting regulations, which was largely to address the ongoing coronavirus pandemic, so it is up to state Legislatures to determine who will cast electoral college votes next week.

Georgia, Pennsylvania, Michigan and Wisconsin all have GOP-controlled legislatures.

“[T]he election of 2020 has been riddled with an unprecedented number of serious allegations of fraud and irregularities,” the brief claims. “National polls indicate a large percentage of Americans now have serious doubts about not just the outcome of the presidential contest, but also the future reliability of tour election system itself.”

There has been no credible evidence of wide-spread fraud, according to the U.S. Justice Department and states’ independent reviews. More than three dozen cases by Trump and his allies attempting to challenge the outcome have been rejected by the courts or dropped for lack of evidence.

Still, Trump has refused to concede the November 3 election to Biden, even as Biden works to roll out key members of his incoming administration.

Trump has spent the weeks since the election constantly tweeting baseless accusations and conspiracy theories about the election outcome and prodding Republicans to help him overturn the election results.

During a summit on COVID-19 vaccine development this week, Trump repeatedly implored for someone to have the “courage” to challenge Biden’s win.