Joe Biden sought to heal rifts in the Democratic party on Sunday by heaping praise on nomination rival Bernie Sanders after a poll showed Donald Trump rapidly closing the gap with the former vice president.

Mr Trump’s approval rating has reached 49 per cent, the highest since he took office, according to a Gallup poll.

The figures suggest the Democrat attacks on the administration’s management of the coronavirus crisis have not hit home, even though the United States is bracing itself for massive job losses in the wake of the coronavirus outbreak.

The surge in support for Mr Trump, who has given daily press conferences during the crisis, comes at a time when he has secured bipartisan support for a $2 trillion economic rescue package.

He has also invoked the Defence Production Act to order GM, one of America’s big three carmakers, to make much-needed ventilators for the country’s hospitals.

The ABC-Washington Post poll released on Sunday gave Mr Biden a narrow two-point lead over Mr Trump.

Even though other polls put Mr Biden further ahead, the surge in the president’s approval rating will have set alarm bells ringing among Democrat strategists.

Mr Biden, who now looks almost certain to win the Democratic nomination for November's presidential election, was careful not to put pressure on Mr Sanders to abandon his campaign when he appeared on NBC’s Meet the Press yesterday.