Republican presidential candidate Donald Trump (L) and Democratic presidential candidate Hillary Clinton participate in the second presidential debate at Washington University in St. Louis, the United States, on Oct. 9, 2016. [Photo/Xinhua]

LAS VEGAS/NEW YORK -- New revelations about US Democratic nominee Hillary Clinton's email controversy is to provide new ammunition for her Republican rival Donald Trump in their third and final presidential debate.

Adding to voters concern amid Trump's claim that the Nov. 8 election was rigged against him, the line of attack on emails may hurt Clinton in the final stretch of their race to the White House, political analysts said.

But it will not help Trump either to regain a footing in women voters and undecided voters as Clinton will sharpen an old weapon in her hand by attacking the New York real estate billionaire over women accusations of his sexual misconduct, they said.

RIGGED ELECTION & EMAILS

In their 90-minute showdown due on Wednesday night in Las Vegas, Trump is expected "to focus on the election being 'rigged' by the media and the Clinton campaign and economic interests," Robert Shapiro, a professor and former chair of the Department of Political Science at Columbia University, told Xinhua.

"He will especially bring up the WikiLeaks emails and other emails that incriminate the Clinton campaign," he said.

The email scandal was once again thrust into the presidential campaign on Monday when the FBI published documents containing the allegation of the State Department trying to arrange a "quid pro quo" to reduce the classification of an email from Clinton's private server regarding the deadly 2012 attack on a US compound in Benghazi, Libya.

The emails "will be a line of attack" as the moderator -- Chris Wallace - will also bring this up since he is from Fox News which has been covering this scandal extensively, the professor said.

Dave Robertson, professor and chair of Department of Political Science at the University of Missouri, also believed that Trump will criticize Clinton harshly for the latest email disclosure.

Trump "will charge that the State Department under her leadership was corrupt because it tried to cover up embarrassing information," he told Xinhua.

But both professors believed that the new accusations against Clinton will carry limited killing power as the emails scandal which has been unfolding for over a year has already inflicted wounds on the trustworthiness of the former secretary of state and the first lady.

Days into their final face-off, Trump has been voicing doubts that massive fraud is rigging the election against him.

"The election is absolutely being rigged by the dishonest and distorted media pushing Crooked Hillary - but also at many polling places - SAD," Trump wrote on Twitter on Sunday, without providing details.

"Many of Trump's voters may accept his claim that the election is rigged, but most other voters will reject it," Prof. Robertson said. "It will not turn the tide in Trump's favor."

"A number of Americans, however, are concerned that a few of Trump's supporters would use this claim as an excuse for violence on Election Day and after an election defeat," he added.