WASHINGTON (Reuters) - Republican presidential candidate Donald Trump will "100 per cent" accept the results of the US election if it is fair, his son Eric Trump said on Sunday (Oct 23).
"I think what my father is saying is, 'I want a fair election'," Mr Eric Trump said on ABC's This Week.
"If it's a fair outcome, he will absolutely accept it. There's no question about that."
Trump campaign manager Kellyanne Conway acknowledged on Sunday that Mr Trump trails rival Hillary Clinton in national and key battle ground state opinion polls.
"We are behind," she said on NBC's Meet the Press, adding that Mrs Clinton had "tremendous advantages", including a larger campaign war chest that she can use to buy television commercials.
As the polling gap has widened, Mr Trump has repeatedly said the election is being "rigged" against him. He has not offered evidence and numerous studies have shown that the US election system, which is decentralised and run by the states, is sound.
At last week's debate with Mrs Clinton, Mr Trump challenged a cornerstone of American democracy by refusing to commit to honouring the result of the US election.
"What I'm saying is that I will tell you at the time. I'll keep you in suspense. OK?" Mr Trump said.
In the aftermath of the debate, Mr Trump said he would accept the election outcome "if I win".
The latest Reuters/Ipsos poll released on Friday has Mr Trump trailing Mrs Clinton by 4 percentage point. The latest Reuters/Ipsos States of the Nation project found Mrs Clinton with a 95 per cent chance of winning the needed 270 Electoral College votes.
An ABC News poll released on Sunday morning had Mrs Clinton leading with 50 per cent of likely support, compared to Mr Trump at 38 per cent. The poll found a that the number of Republicans said they were likely to vote fell 7 per cent from mid-October.
Ms Conway was also pressed on Sunday on CNN's State of the Union on whether Mr Trump would accept the election results.
"The system is rigged, especially against the little guy," said Ms Conway without directly responding to the question.
She spoke of any challenges to the election results as"hypothetical".
The efforts by members of Mr Trump's inner circle to downplay his remarks about the integrity of the election indicate he would come under significant pressure to accept the result if he were to lose.
Republican Party chairman Reince Priebus said that by asking Mr Trump to agree to concede, the media was making an extraordinary request. He said Mr Trump would only fight if the election were close and is not trying to dispute a fair election.
"That's not quite what he's saying. What he's saying is he wants to reserve all options and if there is ground for a recount I'll reserve all options," Mr Priebus said on CBS's Face The Nation.
Mrs Clinton and Mr Trump will campaign on Sunday in the key swing states of Florida and North Carolina, where the latest polls show they are within only a few points of each other.
On Sunday, Mr Trump picked up his first endorsement of the general election from a major newspaper when the Las Vegas Review-Journal backed his candidacy. The newspaper is owned by Republican mega-donor Sheldon Adelson, who has been reluctant to donate to Mr Trump.
In 2012, Mr Adelson spent about US$150 million (S$209 million) trying to help elect Republican Mitt Romney.