US President Donald Trump and his predecessor, Barack Obama, have directed slotxo blistering attacks at each other during rival rallies.

Campaigning for Democratic White House nominee Joe Biden in Pennsylvania, Mr Obama likened Mr Trump to a "crazy uncle" and said he emboldened racists.

In North Carolina, the Republican president mocked Mr Obama for being wrong about the 2016 election outcome.

With 13 days to go until this election, Mr Biden holds a solid lead nationally.

But the margin is slimmer in the handful of US states that could go either way and ultimately decide the outcome on 3 November.

Americans are voting early at a record pace this year, with 42 million having already cast ballots both by post and in person.

What did Trump say?

Mr Trump trained most of his fire during his rally in Gastonia on Wednesday evening on his current Democratic challenger for the White House.

He said the choice for voters was between a "Trump super-recovery" or a "Biden steep depression".

Mr Biden has been off the campaign trail all week preparing for the final presidential debate on Thursday night in Nashville, Tennessee, while Mr Trump holds rallies across the battleground states.

The president could not resist taking a pop at Mr Obama, who hit the campaign trail in person about an hour earlier for the first time since the August political conventions.

"There was nobody that campaigned harder for crooked Hillary Clinton than Obama, right?" Mr Trump told supporters, who booed at the mention of his old adversaries' names. "He was all over the place."

The president added: "I think the only one more unhappy than crooked Hillary that night was Barack Hussein Obama."

Mr Trump also mocked Mr Obama's reported initial lack of enthusiasm for the White House bid of Mr Biden, who was his vice-president from 2009-2017.

In 2016, Mr Obama reportedly pressured Mr Biden to sit out the race and allow Hillary Clinton to run, believing she had the better chance of defeating Mr Trump.

Last year Mr Obama said there was a need for "new blood" in the Democratic leadership, which was widely interpreted as a slight against Mr Biden.