Joe Biden leads Donald Trump by 50 per cent to 44 per cent among registered voters, according to a new poll from Quinnipiac University, up from just a one-point lead in December.

       The Democrat is getting stronger among women voters, the survey released on Wednesday indicates, leading his predecessor by 58 to 36 per cent.

       Mr Trump’s Republican challenger Nikki Haley is meanwhile going after both the front-runner for her party’s nomination and the incumbent president in her latest attack ads, capitalising on the lack of appetite for a rematch of the 2020 contest among the American electorate by characterising the 77 and 81-year-olds as reclusive, stingy and out of touch “grumpy old men”.

       Ms Haley has come out swinging against Mr Trump since losing the New Hampshire primary last week, concentrating her campaigning efforts on her native South Carolina and warning voters in a Newsmax interview that he cannot win over suburban women and independent voters, which could stop him beating Mr Biden in November.

       While the 45th president has been preoccupied by his legal troubles since New Hampshire, his rival has attempted to pitch herself as a Tea Party original in an explicit appeal to his base.