Donald Trump has dismissed Barack Obama’s time in the White House as a “disaster” after the US president said he was not fit to succeed him, according to a BBC report.
“He’s been weak, he’s been ineffective,” Republican candidate Mr Trump said of Mr Obama in a Fox News interview on Tuesday.
Mr Obama has questioned why Mr Trump’s party hasn’t disowned him.
Mr Trump has also turned on two senior figures in his own party who have publicly criticised him.
In an interview for the Washington Post, he refused to endorse House Speaker Paul Ryan and Senator John McCain, who are up for re-election in November.