It is the first of three planned presidential debates.
An estimated 90 million people were expected to watch the Democratic and Republican candidates go toe-to-toe for 90 minutes starting at 9.00pm (9.00am Singapore time Tuesday) on the stage at Hofstra University in NY. The gap between the two candidates in recent national opinion polls has narrowed in the past week, with the latest Reuters/Ipsos polling showing Clinton ahead by 4 percentage points, with 41 percent of likely voters. "But most politicians have at least a few raisins, and Hillary ... has more raisins than average".
On Monday, a national poll by Quinnipiac University also found them in a virtual dead heat, with Clinton at 43 per cent to Trump's 42 among likely voters.
This compares to a 41 to 39 percent Clinton lead among likely voters, with Johnson at 13 percent and Stein at 4 percent, in a September 14 survey.
"The temperament question could be one of the areas that can be affected by the debate, and it's an area where Trump is far behind, " Murray said.
Trump will be the first major party presidential nominee to debate a female opponent, and that fact alone will influence his strategy and approach.
It's highly probable, as Donald Trump recently referred to an education issue as "the civic-rights issue of our time". In seeking his first elected office, Trump will argue that the former first lady, USA senator, and secretary of State is the embodiment of a failed political establishment and that he is the true candidate of change. The New York businessman plans to argue that Clinton may have experience but has made "bad decisions" throughout her career.
Both Clinton and Trump go into the debate with high negative ratings, which they hope to alter with their performance. Only 38 per cent had a positive impression of Trump, to Clinton's 39 per cent.