Republican presidential candidate Donald Trump smiles during a campaign rally at the Delaware County Fair, Thursday, Oct. 20, 2016, in Delaware, Ohio.

Image Credit: AP Photo/ Evan Vucci

WASHINGTON - Donald Trump smiled and pointed into a roaring crowd as he told a joke nobody's ever heard before — about a presidential nominee threatening to ignore the results of an American election.

Supporters cheered madly Thursday as Trump, fresh from another must-see TV appearance in the third and final presidential debate, kicked off a campaign speech in Ohio by saying he had a "major announcement" to make.

"I would like to promise, and pledge, to all of my voters and supporters, and to all of the people of the United States, that I will totally accept the results of this great and historic presidential election," he said, straight-faced.

Then, a pause before the punchline: "... If I win."

The crowd went wild. But prominent Republicans aren't laughing.

Several of the latter expressed dismay over the potential electoral ripple effect from his remarks, which started the previous night where, with countless millions watching live, he refused to say whether he'd respect the result.

As the comments made international headlines, and presidential historian Michael Beschloss said he couldn't recall a precedent for such remarks in U.S. history, Trump teased out the controversy an extra day.

Later in Thursday's speech, Trump elaborated with a more boilerplate statement: of course, he said, he would accept the result — barring some irregularity or need for a recount.

''I would accept a clear election result. But I would also reserve my right to contest or file a legal challenge in the case of a questionable result.'' He capped it off by saying, five times, that he's going to win anyway.

A number of fellow Republicans are worried that their entire congressional wing is about to be dragged down by their candidate, whose electoral prospects are dimming by the day and whose late-campaign behaviour has fuelled rumours that he's more interested in starting a media company than helping Republicans save seats.

They have reason to worry, according to a political science professor who's studied voter motivation.

Adam Levine of Cornell University co-authored a paper this year that suggests warnings about vote-rigging seriously depress voter participation. He says it's most dramatic among people likely to trust the person delivering the message, in this case Trump's fans.

Levine posted four different messages in Google ads that popped up when people searched for voter registration information — about the system being rigged; the wealthy buying elections; people's voice not being heard; and the more positive message, ''Be heard.''

The first two messages reduced ad-clicks up to 46.7 per cent.

"It totally demobilized people," Levine said in an interview. "(It) totally went down, in a very dramatic way."

That's a problem for the Republican party — which is struggling to retain control of Congress. Its hold on the Senate is in jeopardy, and it now faces the once-unthinkable prospect that its stranglehold on the House might be significantly weakened, if not threatened.

Some Republicans in tight races have distanced themselves from Trump. Sen. Kelly Ayotte of New Hampshire said Thursday: ''As a former attorney general, I believe he should accept the result.''

She received support from colleagues like Lindsey Graham, a South Carolina senator: ''Mr. Trump is doing the party and country a grave disservice.... If he loses it will not be because the system is 'rigged' but because he failed as a candidate.''

Yet the party is deeply divided.

Some can afford to brush off the nominee, if they live in a swing state like Ayotte, or if they're not facing a primary any time soon, like Graham. For many other Republicans, Trump is a live grenade to be handled with care.

Ask Paul Ryan.

The House Speaker's popularity has plunged in recent days. Different polls now suggest Ryan has far less support within the party than Trump, likely because he's been aloof and has distanced himself from the nominee.

Now Trump cheerleaders in the conservative media are demanding Ryan's head. Sean Hannity of Fox News has called for a post-election coup, and proposed a few possible replacements from the more Trump-friendly wing of the party.

One of those touted replacements appeared to encourage that talk Thursday. Congressman Mark Meadows of North Carolina thanked a radio-station host in his home state on the air for bringing up the possible putsch.

''It is picking up some steam,'' Meadows said.

''A lot of the people who believe so desperately that we need to put Donald Trump in the White House — they question the loyalty of the Speaker.''

He said Republicans will revisit the issue after the Nov. 8 election.

News from © iNFOnews, 2016