A coalition of 11 Republican senators announced Saturday it will challenge the outcome of the presidential election by voting to reject electors from some states when Congress meets next week to certify the Electoral College results that confirmed President-elect Joe Biden won.

President Donald Trump’s extraordinary refusal to accept his election defeat and the effort to subvert the will of the voters has become a defining moment for Republicans and is tearing the party apart.

Senate Majority Leader Mitch McConnell has urged Republican not to try to overturn the election.

The 11 senators, led by Ted Cruz of Texas, said they will vote against certain state electors unless Congress appoints an electoral commission to immediately conduct an audit of the election results. They acknowledged they are unlikely to change the results of the election.

“We intend to vote on January 6 to reject the electors from disputed states as not ‘regularly given’ and ‘lawfully certified’ (the statutory requisite), unless and until that emergency 10-day audit is completed,” they wrote in the statement.

“We do not take this action lightly,” they said.

In response to Trump’s unfounded claims of voter fraud, bipartisan election officials and Trump’s then-Attorney General William Barr have said there was no evidence of widespread fraud and the election ran smoothly.

The days ahead are expected to do little to change the outcome. Biden is set to be inaugurated January 20 after winning the Electoral College vote 306-232.

Senator Josh Hawley of Missouri was the first to defy McConnell by announcing he would join House Republicans in objecting to the state tallies during Wednesday’s joint session of Congress.

On the other side of the party’s split, Senator Ben Sasse of Nebraska warned such challenges are a “dangerous ploy” threatening the nation’s civic norms.

The issue is forcing Republicans to make choices that will set the contours of the post-Trump era and an evolving GOP.

Caught in the middle is Vice President Mike Pence, who faces growing pressure and a lawsuit from Trump’s allies over his ceremonial role in presiding over the session Wednesday.