Obama, who governed for two terms and remains one of the most popular figures in the Democratic Party, blasted Trump for his handling of the coronavirus pandemic, noting that the president himself had fallen victim to the virus.

“Donald Trump isn’t suddenly going to protect all of us,” he said. “He can’t even take the basic steps to protect himself.”

Obama’s appearance filled a gap left by Biden, who has stayed at home in Delaware since Monday for meetings and preparation ahead of his Thursday debate with Trump in Nashville, Tennessee.

Earlier in the day, Obama spoke to black community leaders in Philadelphia.

“I’ve never lost hope over these last four years,” Obama said. “I’ve been mad. I’ve been frustrated, but I haven’t lost hope, and the reason is because I never expected progress to move directly in a straight line.”

01:07

‘They would have called me Beijing Barry’: Obama taunts Trump about Chinese bank account

‘They would have called me Beijing Barry’: Obama taunts Trump about Chinese bank account

Americans are voting early at a record pace this year, with 42 million ballots cast both via mail and in person ahead of the November 3 election, on concerns about the coronavirus and to make sure their votes are counted.

The record early vote so far represents about 30 per cent of the total ballots cast in 2016, according to the University of Florida’s US Elections Project.

While Obama was speaking, Trump headed to North Carolina, another battleground state where opinion polls show a tight race, for a rally in Gastonia on Wednesday evening.

Trump’s cash woes mount as Biden laps him

Biden’s running mate, Kamala Harris, was also in North Carolina to mobilise voters in Asheville and Charlotte.

The last days of campaigning are taking place amid a surge in new cases of Covid-19 and hospitalisations in battleground states, including North Carolina and Pennsylvania but also Wisconsin, Ohio and Michigan.

Pennsylvania has averaged 1,500 new cases a day over the past week, a level it has not seen since April, according to a Reuters analysis. North Carolina is averaging 2,000 new cases a day over the past week, its highest level ever. The virus has claimed the lives of more than 221,000 Americans.

Polling shows a majority of voters are disappointed in the way Trump has handled the pandemic, which he has repeatedly said would disappear on its own.

On a call organised by the Biden campaign and Texas Democrats on Wednesday, several Texas Republicans urged fellow conservatives to vote for Biden, citing the coronavirus crisis as well as Biden’s character.

“This is not a decision I took lightly. I love the GOP, and I love most GOP officials. But I love my country more,” said Jacob Monty, a Republican immigration lawyer who resigned from Trump’s national Hispanic advisory council in 2016.

What Michigan’s Covid-19 experience says about Trump’s re-election hopes

Biden and Trump are expected to meet in their second and final debate on Thursday night, giving the Republican an opportunity to change the trajectory of a race that Biden is leading in national polls.

Biden believes he must win his birth state of Pennsylvania and has visited it more than any other state during the campaign. Trump narrowly won the state over Democrat Hillary Clinton in 2016.

Trump has gained ground there, according to a Reuters/Ipsos poll released on Monday, which showed the challenger leading by 49 per cent to 45 pre cent, slightly narrower than a week earlier.

“If we win Pennsylvania, we win the whole thing,” Trump said on Tuesday at a rally in Erie, in the state’s northwestern corner.