Paul Singer

USA TODAY

Twenty-six percent of Republican governors and members of Congress are refusing to endorse GOP presidential nominee Donald Trump, according to a survey by the USA TODAY Network.

Of the 31 Republican governors, 54 GOP senators and the 246 Republican members of the House (331 total), the survey identified 87 who are not endorsing Trump's candidacy as of late Tuesday.

It is an extraordinary demonstration of the fracture Trump’s candidacy has revealed in the Republican Party. There is no precedent in modern American political history for elected officials of either party to refuse en masse to support their presidential nominee. It shows that Trump will have to wage a national campaign without the fleet of surrogates and supporters that every other presidential contender has relied on for decades to help bring voters to the polls. And it illustrates how hard it will be for the GOP to rebuild if Trump loses.

Some of these elected officials rejected Trump months ago; many turned on him since the release of a 2005 tape of Trump making lewd comments about women; and some simply refuse to say whether they will or will not vote for their party's presidential nominee.

Track GOP leaders who don't support Trump

By way of comparison, in September 2012, The Hill newspaper wrote that only "a handful" of Republican lawmakers were declining to support GOP nominee Mitt Romney, naming only three. Of those, only one, Justin Amash of Michigan, is still in Congress. Amash has refused to endorse Trump as well, and tweeted Saturday, "He should have stepped aside long ago."

This is one reason why Trump on Tuesday took on the party in a series about tweets about Speaker Paul Ryan and other Republican leaders.

Trump declares war on establishment Republicans

Sen. Ben Sasse of Nebraska was the first Republican senator to say he would not vote for Trump, saying in a February Facebook post, "if Donald Trump ends up as the GOP nominee, conservatives will need to find a third option." Nineteen of his GOP Senate colleagues have now joined him. Eleven Republican governors are also not on "Team Trump," and 57 members of the House have declined to support him, according to the USA TODAY Network tally.

Trump's "offensive comments make it very difficult for any candidate to support him," said Fred Malek, a longtime Republican strategist and finance chair for the Republican Governors Association. "Therefore you have an unheard of number looking to their own election prospects and feeling they are better served by not supporting him."

Malek said he believes the remarkable number of dissenters in the party represent concerns about Trump, not a deeper fissure in the party, and that the party will be able to reunite in the next election cycle even if Trump loses.

Tyler White, a political science professor at the University of Nebraska, disagrees. "We are seeing a diversity in the Republican Party that we are not used to," White said. Democrats have a reputation for being fractious and hard to organize; Republicans have been the party "with a reputation of being in lock step with one another, and decisions are made by the 'adults' in the party."

What has changed, White said, is "this giant debate going on within the Republican party about who their base really is. Is it based on immigration and cultural issues. or is to the the group that is more focused on national security and fiscal responsibility?"

Ryan's time as House speaker illustrate the challenge of trying to bridge that divide. Ryan took the speakers' gavel only after conservative hard-liners pushed out his predecessor, John Boehner of Ohio. Ryan hesitated in endorsing Trump, saying first that he wanted to make sure Trump shared the policy agenda of House Republicans; he later endorsed Trump but continued to scold the candidate for inflammatory comments. On Monday, Ryan did not withdraw his endorsement, but said he would not campaign with Trump and he urged other Republicans to do whatever was best for their own re-election.

Contributing: Holly T. Moore

2016 Poll Tracker - USA TODAY