Trump says his campaign will demand Joe Biden be drug tested ahead of presidential debates

President offers no medical evidence to support his latest bold claim about a political opponent

Donald Trump, offering no medical evidence, has suggested Joe Biden was drugged when he debated Bernie Sanders and said he wants the former vice president drug-tested before they go toe-to-toe.

The president made his latest bold declaration ahead of night No 3 of the Republican National Convention, and threatened to distract from the biggest speech of vice president Mike Pence’s political career as the GOP ticket trails Mr Biden and running mate Kamala Harris in national polls and ones taken in most key battleground states.

Mr Trump told the Washington Examiner during an Oval Office interview published on Wednesday that he thought Mr Biden was incoherent during debates with almost a dozen other Democratic candidates. But, suddenly, when the field was down to just himself and Mr Sanders, the president claims he saw a different former VP on the debate stage.

“Nobody thought that he was even going to win,” Mr Trump said. “Because his debate performances were so bad. Frankly, his best performance was against Bernie.”

Then he dropped a bombshell.

“We’re going to call for a drug test, by the way, because his best performance was against Bernie. It wasn’t that he was Winston Churchill because he wasn’t, but it was a normal, boring debate,” he added. “You know, nothing amazing happened. And we are going to call for a drug test because there’s no way – you can’t do that.”

Asked by an Examiner reporter, “What do you think was going on?”, the president offered nary a shred of evidence.

“I don’t know how he could have been so incompetent in his debate performances and then all of a sudden be OK against Bernie,” he replied. “My point is, if you go back and watch some of those numerous debates, he was so bad. He wasn’t even coherent. And against Bernie, he was. And we’re calling for a drug test.”

A Biden campaign spokesman had not yet responded to an inquiry seeking a reaction.

The incumbent, down in RealClearPolitics’ average of polls by over 7 percentage points nationally and by at least 5 points in a handful of crucial swing states, compared his general election clash with Mr Biden to a championship boxing match.

“Well, it is a prizefight,” Mr Trump said. “It’s no different from the gladiators, except we have to use our brain and our mouth. And our body to stand. I want all standing; they want to sit down.”

When pressed during the interview to support his claims of a drugged Democratic nominee, as he often does the president merely lobbed new accusations towards an opponent while claiming to have natural medical acumen. (Mr Trump went to business school, and has no medical training).

“All I can tell you is that I’m pretty good at this stuff,” he said. “I look. I watched him in the debates with all of the different people. He was close to incompetent, if not incompetent, and against Bernie, he was normal ... and I say, ‘How does that happen?’”