The father of a Muslim American soldier killed in Iraq, whose recent speech gained him international fame, has lashed out at the US Republican Party.

In an interview with Al Jazeera's Mehdi Hasan, the host of UpFront, Khizr Khan condemned the Speaker of the House, Paul Ryan, and Senate Majority Leader, Mitch McConnell, for failing to withdraw their endorsement of Republican presidential nominee Donald Trump.

"They are being cowards in a moral sense," Khan said.

Asked if top Republicans would eventually withdraw their endorsement for Trump, Khan answered: "It is coming. I assure you ... The moral dilemma in his candidacy is coming full circle." 

Khan, whose son Humayun was killed in Iraq in 2004, spoke on the closing night of the Democratic National Convention.

His remarks, especially those criticising Trump, went viral.

"Americans are not going to buy the snake oil he is selling," Khan told Al Jazeera.

READ MORE: Trump and the Khans

The billionaire and former reality television star who hopes to lead the US was "incapable intellectually and mentally" of understanding how he has helped boost recruitment for the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group with his "fear-mongering", Khan said.

During the interview, Khan, who has roots in Pakistan, said that he had opposed the US invasion of Iraq in 2003.

"That was a mistake that has not served American interests well," he said.

"[Hillary Clinton] supported it, but it was the Republican party's starting and doing of the Iraq war," he added. “If I criticise Hillary Clinton on her policies, it is received well. The person who criticises is not condemned."

ISIL recently called Khan's late son an "apostate".

"That [ISIL] is a perverted version of Islam," Khan said. "Islam has nothing to do with this kind of violence".

Watch the full interview with Khizr Khan on Al Jazeera at 19:30GMT on Friday, or visit UpFront online

Source: Al Jazeera