President Barack Obama has said Republican nominee Donald Trump is unfit to be president, and questioned why his party still supports the New York billionaire’s candidacy.
“There has to come a point at which you say: ‘Enough’,” Mr Obama said.
Mr Trump has been sharply criticised for attacking the parents of a fallen US soldier who spoke out against him.
He has also been condemned for backing the Russian annexation of Crimea.
Mr Obama said he had had policy differences with previous Republican presidents and candidates – but added that he had never thought they could not function as president.
At last week’s Democratic National Convention, Khizr Khan – a Muslim whose son was killed serving in the US military in Iraq – criticised Mr Trump’s plan to temporarily ban Muslims from entering the US.
Mr Trump responded by attacking the “Gold Star” family, the term for families that have lost a relative in war. Democratic and Republican leaders as well as veterans’ groups quickly condemned him.
I feel like we’re seeing the Clinton campaign’s strategy for handling Trump play out: keep him in a constant fight against various surrogates and proxies, all calculated to damage him with swing voters, while Hilary remains above the fray. Trump’s brand is all about dominance and winning so he has to engage with these attacks from democratic surrogates – otherwise he’d look weak. And he, personally seems unable to see these traps for what they are, so he repeatedly blunders straight into them. Let’s see what his response to Obama is.