Donald Trump has declared he will in fact accept the election result … if he wins.

The Republican presidential candidate used a rally in Ohio to explain his warning that he won’t accept the results on November 8 if there is a “questionable result”.

But Mr Trump bushed off the possibility of that happening, declaring to the crowd “we’re not going to lose”.

“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,” Mr Trump said.

He waited a few moments before adding a delayed: “If I win”.

He later told the rally that he would “of course” accept a “clear” election result, but reserved the right to file a legal challenge if he lost.

It comes a day after he refused to promise he would trust the outcome if he loses.

“Of course, 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,” Mr Trump said.

His refusal to commit to the time-honoured American tradition of gracefully acceding to the winner throws up a number of hypothetical election-day scenarios.

And despite Mr Trump’s repeated warning of impending, widespread voter fraud, no evidence supports his claim, with plenty of evidence to the contrary.

Asked at the debate whether he would accept the outcome, Mr Trump said: “I will tell you at the time. I will keep you in suspense.”

Democratic candidate Hillary Clinton called the comments “horrifying”, while several prominent Republicans also denounced Mr Trump’s position.

Some worried his stance might make it more difficult for his party to hold on to control of Congress.

‘Concession is an act of respect for the American people’

John McCain has said accepting the election result is “the American way”. Photo: Getty

Senator John McCain, of Arizona, who lost the 2008 presidential election to Democrat Barack Obama, issued a strong statement saying that accepting the election result is “the American way”.

“I didn’t like the outcome of the 2008 election. But I had a duty to concede, and I did so without reluctance,” Mr McCain said.,

“A concession isn’t just an exercise in graciousness. It is an act of respect for the will of the American people, a respect that is every American leader’s first responsibility.”

Democrats jumped to ask Republican candidates whether they agreed with Mr Trump, who is making his first-ever run for public office and against Mrs Clinton, a former first lady, senator and secretary of state.

Mr Trump’s vice presidential running mate, Governor Mike Pence of Indiana, said Mr Trump “will accept the outcome” because he is going to win.

In recent weeks, Mr Trump has stepped up allegations that the election is being rigged, though he has not offered specific evidence.