Trump arrives on a debate stage today in St Louis with his presidential campaign in crisis and his party in open rebellion against him.
Some Republican figures have spoken out against Trump, after the release of a 2005 video over the weekend in which he talks about women in vulgar and degrading terms.
In it, he is heard discussing his attempts to bed a married woman, and bragging that he can "do anything" to women because he is a celebrity.
"When you're a star, they let you do it. Grab them by the pussy. You can do anything," he says.
WARNING: The below video contains graphic language
The debate at Washington University, which starts at 2pm NZT, has some party leaders worried Trump will make matters worse by attacking Democrat Hillary Clinton through the infidelities of her husband, former President Bill Clinton.
Fallout from the 2005 video, which played repeatedly on television all weekend, is likely to overshadow other topics at the debate.
After the video's release, CNN also uncovered audio of Trump talking with radio shock-jock Howard Stern in which the two men engaged in lewd conversations about women, including Trump's daughter, Ivanka.
The debate will be a town hall-style event, with about half the questions coming from uncommitted voters screened by Gallup, and the rest posed by moderators Martha Raddatz, of ABC News, and Anderson Cooper, of CNN.
- Additional reporting news.com.au
