Democratic presidential nominee Joe Biden on Wednesday refused to speculate about Donald Trump’s health, after tweets from the US President insisting he had not suffered “mini-strokes.”
Mr Trump visited Walter Reed Hospital last year in what has become a point of speculation after a new book said Vice President Mike Pence was put on standby at the time.
But Mr Biden did not wade into the debate.
“I’m not going to speculate on what it means,” he said. “I can say nothing this administration does is normal, so I’m not being facetious when I say that.
"Who in God’s name knows what it’s all about. I just don’t know. I don’t know and I’m not going to speculate. I’ll let the experts do that.”
Mr Biden said he was never put on standby when former president Barack Obama went for medical exams.
“The only time that I have been on notice is when the President’s out of the country and I’m in the country,” he said.
Mr Trump took to social media this week to staunchly deny, without being prompted, that he had suffered a series of strokes last year.
In 24 hours, he posted at least four times on Twitter that he did not have “mini-strokes” last year and dismissed any such reports as fake news.
The White House said the unscheduled visit to the Walter Reed Hospital was for routine tests before a busy 2020.
"It never ends," Mr Trump tweeted early on Tuesday.
"Now they are trying to say that your favourite president, me, went to Walter Reed Medical Centre, having suffered a series of mini-strokes.
"Never happened to this candidate. Fake news.”
White House doctor Sean Conley released a statement confirming the president had not suffered a stroke, mini-stroke or
"any acute cardiovascular emergencies, as have been incorrectly reported in the media".
Pulitzer Prize-winning journalist Michael Schmidt's book, Donald Trump v the United States, claims Mr Pence was told to be ready to take over the president's role after Mr Trump visited Walter Reed.
"In the hours leading up to Mr Trump's trip to the hospital, word went out in the West Wing for the vice president to be on standby to take over the powers of the presidency temporarily", if Mr Trump had to have an operation, Schmidt wrote.
Mr Pence did not deny that in an interview with Fox News on Tuesday evening. “I can’t recall," he said.
A vice president is “always on standby", Mr Pence said.
After his comments, Mr Trump again denied that his vice president was told to be on standby.
"Mike Pence was never put on standby and there were no mini-strokes," he tweeted.
"This is just more fake news by CNN, a phoney story.
"The reason for the visit to Walter Reed, together with the full press pool, was to complete my yearly physical. Short visit, then returned" with the media to the White House.
A statement by the Trump campaign followed, accusing CNN commentator Joe Lockhart of tweeting “reckless speculation".
Mr Lockhart questioned whether Mr Trump had a stroke:
Now the campaign wants CNN to sack Mr Lockhart, who served as White House press secretary in the Clinton administration.
“If another CNN employee said similar things about Barack Obama they’d be fired immediately, so the same standard should be applied here,” the campaign said.
But after Mr Trump’s tweets, the speculation about a stroke has only grown.
Conservative website the Drudge Report published pictures of him dragging his right foot and hinting that he might have had a stroke.
The headline prompted yet another tweet from Mr Trump, this time attacking the website.
“Drudge didn’t support me in 2016 and I hear he doesn’t support me now,” he said.
The website ran pro-Trump headlines in 2016.
The Trump campaign is trying to shift the conversation to the mental health of Mr Biden, 77.
On Wednesday, ABC reported that the Department of Homeland Security withheld publication of an intelligence bulletin warning of a Russian scheme to push "allegations about the poor mental health" of Mr Biden.
A department official declined to comment.
