Barack Obama: Donald Trump ‘woefully unfit to be president’

US president Barack Obama has declared Donald Trump “unfit” and “woefully unprepared” to serve in the White House.

In a searing denouncement, Mr Obama challenged top Republicans to drop their support for their party’s nominee, declaring: “There has to come a point at which you say, ‘enough’.”

The outgoing president’s blistering critique of his potential successor followed Mr Trump’s criticism of an American Muslim family whose son, a captain in the US Army, was killed in Iraq.

A growing number of Republicans have disavowed Mr Trump’s comments, but most of those who have endorsed him are sticking by that stance.

At a White House news conference, Mr Obama said: “If you are repeatedly having to say, in very strong terms, that what he has said is unacceptable, why are you still endorsing him? What does this say about your party that this is your standard bearer?”

The US president said his opposition to Donald Trump is about more than policy differences.

He said while he disagreed with his Republican opponents in the 2008 and 2012 elections, he never thought they were unfit to do the job.

Mr Obama has heightened popularity in his eighth and final year in office. He has made clear he plans to be an active player in the White House race, campaigning around the country for Democratic nominee Hillary Clinton.

The president and first lady Michelle Obama spoke at last week’s Democratic convention in Philadelphia, where Khizr and Ghazala Khan also made an appearance.

Mr Trump responded with a statement that summarised the points he makes in his stump speeches: “Obama-Clinton have single-handedly destabilised the Middle East ... released criminal aliens into our country who killed one innocent American after another ... produced the worst recovery since the Great Depression (and) shipped millions of our best jobs overseas.”

Last week, Khizr Khan criticised Mr Trump’s call for a temporary ban on Muslims coming to the US and challenged whether he had read the American constitution.

Mr Trump has questioned why Ghazala Khan did not speak, implying her religion prevented her from doing so, and has said he was “viciously attacked” by Khizr Khan.

Mr Khan delivered an emotional address at last week’s Democratic convention, with his wife standing by his side. The Pakistan-born Khan told the story of his son, US army Capt Humayun Khan, who was posthumously awarded a bronze star and purple heart after his death in 2004.

Mr Trump’s unwillingness to let the matter subside sparked outrage from several Republicans.

Arizona Senator John McCain, said Trump did not have “unfettered licence to defame those who are the best among us”.