LAS VEGAS, the United States, Oct. 19 (Xinhua) -- As the 2016 U.S. election is heading into the homestretch, Republican and Democratic presidential nominees Donald Trump and Hillary Clinton are expected to ratchet up attacks against each other's controversial issues during the third and last presidential debate on Wednesday in Las Vegas, Nevada.

The following are controversies dogging the two candidates and will likely be brought up in the third debates.

For Trump, the fallout of his past lewd remarks about women and the ensuing accusation from at least nine women for his alleged sexual misconduct continues to take its toll on Trump's polling number and is most likely to be a target for Clinton.

In a leaked audio clip recorded in 2005, Trump made lewd remarks about an unidentified married woman he hoped to have sex with, boasted about how easy it is to attract women with his celebrity status and even talked about groping women.

When you're a star, women let you do anything, he was recorded as saying.

The New York billionaire later apologized for the "locker room banter" in the audio, but claimed that his Democratic rival Hillary Clinton's husband, former President Bill Clinton, "has said far worse to me on the golf course -- not even close."

Since the second debate on Oct. 9, at least nine women came forward and accused Trump of either kissing or groping them without consent, which the Trump campaign denied strongly.

Also, Trump's acknowledge that he had avoided paying federal income taxes for years is also likely to be a target for Clinton.

During the second debate, Trump acknowledged for the first time that he used an almost 1 billion U.S. dollars loss reported on his 1995 income tax returns to avoid paying federal income taxes for more than a decade.

For Clinton, the third debate could prove to be more volatile than the last two with more damaging revelations of her congenial relations with Wall Street and a possible "quid pro quo" between the U.S. State Department and the Federal Bureau of Investigation (FBI) on the federal investigation of Clinton's email practices.

According to what appeared to be parts of transcripts of Clinton's paid speeches to Wall Street leaked through hacked emails from Clinton campaign chairman John Podesta, Clinton once implied that action was necessary to curb Wall Street "for political reasons", and the former secretary of state once contemplated the necessity of holding "both a public and a private position" on politically contentious issues.

Also, days before the third debate, the revelation of possible "quid pro quo" in Clinton's email probe again highlighted the candidate's trust deficit with the voters.

According to the latest batch of FBI documents released on Monday, one official from FBI alleged that Undersecretary of State for Management Patrick Kennedy asked for a classified email handled via Clinton's private email setup to be downgraded to unclassified in exchange for more overseas dispatch for FBI agents.