With Hillary Clinton struggling to see off the challenger of Bernie Sanders, bookmakers William Hill have lengthened her Presidential odds slightly from 4/11 to 2/5.
William Hill have also shortened Donald Trump's odds from 5/2 to 9/4 to be the next President of the United States.
William Hill spokesman Graham Sharpe told BetOnPolitics.co.uk: "Although she is still comfortably heading the Presidential market, Hillary Clinton's continued struggle to see off the challenge of Bernie Sanders is deterring some political punters from backing her to win the race to the White House.
"They seem to be feeling that if she cannot brush aside an unfancied contender from her own Party, how much more difficult might she find it to defeat a seasoned campaigner like Mr Trump?"
Latest William Hill US Presidential Election odds: 2/5 Clinton; 9/4 Trump; 20/1 Sanders.
To be Democrat candidate: 1/25 Clinton; 10/1 Sanders.