William Hill now thinks that Clinton and Trump are so far ahead of their rivals in the nomination stakes that they look past the post.
The bookie is now offering odds of 1/14 for Clinton to win the Democrat nomination, while Trump is being offered at 1/5 to win the Republican nomination.
They are also dominating the betting on who will become President, with Hillary 4/6 favourite and Trump 9/4 second favourite.
The news comes after Hillary Clinton won the South Carolina primary ahead of the senator Bernie Sanders. Clinton resoundingly won the contest with 73.5 per cent of the vote, compared to Sanders' 26 per cent.
Clinton was widely expected to win the primary, but the vote gives her momentum moving into "Super Tuesday", when 11 states and one territory will vote on one day.
On the Republican side of the race, Donald Trump won his third primary when he triumphed over the rest of the pack in Nevada.