US Elections

Hillary Clinton was explaining her plans to raise taxes on the wealthy when she pointedly referred to Trump's possible tax avoidance: "My social security payroll contribution will go up, as will Donald's, assuming he can't figure out how to get out of it."

Trump's retort? "Such a nasty woman."

It quickly became one of the defining quotes of the night on social media.

This raises the possibility of an extraordinary departure from principles that have underpinned American democracy for more than two centuries.

"I will look at it at the time," Trump said when asked during the final presidential debate whether he would concede if he loses on November 8, following his claims that the election is "rigged" against him.

He added: "I will keep you in suspense."

Hillary Clinton will be joined at Wednesday's debate by two well-known billionaires who are backing her campaign, in what may be an attempt to rattle Republican nominee by su btly questioning his own net worth.

Meg Whitman, the Hewlett-Packard CEO and former Republican California gubernatorial candidate, and Mark Cuban, the outspoken billionaire owner of the Dallas Mavericks, will both be Clinton's guests at Wednesday's third and final presidential debate.

He said Mr Trump's attempt to discredit a poll before it has even taken place was "unprecedented" for a US presidential candidate.

Also "unprecedented", said Mr Obama, was the Republican candidate's "flattery" of Russia's president.

Mr Trump is facing sinking poll numbers and accusations of sexual assault.

The businessman-turned-politician has claimed the 8 November election will be "absolutely rigged" for Democratic candidate Hillary Clinton.

Mrs Trump called those accusations "lies" and saying Mr Trump was "egged on" into "boy talk" during a 2005 tape in which he made lewd comments about women.

"I believe my husband. I believe my husband," she said in an interview with CNN's Anderson Cooper on Monday.

"This was all organized from the opposition. And with the details ... did they ever check the background of these women? They don't have any facts."

She also said she hadn't heard her husband use that kind of language before.

"The flammable substance appears to have ignited inside the building, burned some furniture and damaged the building's interior before going out. The substance was housed in a bottle thrown through one of the building's front windows,"according to a statement by the town of Hillsborough.

His comments appear to contradict his running mate Mike Pence, who told NBC earlier Mr Trump would "absolutely" accept the election result, despite media "bias".

Mr Trump's adviser Rudy Giuliani has also accused Democrats of "cheating".

Polls suggest Mr Trump is losing ground in some of the key battleground states.

Meanwhile Hillary Clinton's running mate Tim Kaine has blasted Mr Trump's election-rigging claims as "scare tactics".

"The other day I'm standing at my podium and she walks in front of me, right? She walks in front of me and when she walked in front of me. Believe me, I wasn't impressed, but she walks in front of me," he said at a campaign rally in Greensboro, North Carolina.

It was not clear what he meant when he said he "wasn't impressed" and a message left with the Trump campaign was not immediately returned. But Trump has commented on women's appearances in recent days, particularly those who have made sexual assault allegations against him.

Speaking to Australia's Sky News in an interview on Thursday, Abbott also dismissed Democratic nominee Hillary Clinton's comments that half of Trump supporters were "deplorables."

"The vast majority of Trump supporters are not deplorables, they really aren't. They're decent people who want to see change inside their country and that's fair enough," he said.

But when asked about controversial comments made by Trump in a leaked video from 2005, Abbott said they were "gross".

The women were Paula Jones, who has accused Bill Clinton of propositioning her and exposing himself; Juanita Broaddrick, who claims Clinton sexually assaulted her; Kathy Shelton, who says Hillary Clinton defended a man who victimized her; and Kathleen Willey, who claims Bill Clinton groped her.

All four are expected to be in the audience tonight.