The race for the White House is rapidly tightening, with polls showing Republican nominee Donald Trump snapping at the heels of his Democratic opponent Hillary Clinton amid concerns about the health of both candidates and calls for more transparency about their medical records.
The latest New York Times/CBS news poll, released yesterday, indicates 44 per cent of likely voters would support Mrs Clinton, while 43 per cent would support Mr Trump.
This is a sharp gain for Mr Trump, who managed only 39 per cent in a similar poll in July, while 46 per cent backed Mrs Clinton.
National polling averages also show Mrs Clinton's lead dropping from 6.8 percentage points this time last month to the current 1.8 percentage points.
The polls come after a bad week for the Clinton campaign. Last week she was roundly criticised for saying half of Mr Trump's voters belonged in "a basket of deplorables". Mr Trump seized on this, saying it showed her contempt for voters.
Mrs Clinton, 68, nearly collapsed at a Sept 11 memorial ceremony in New York on Sunday. She had been diagnosed with pneumonia two days prior but chose to keep it secret, a decision that blew up into concerns about her health and lack of transparency about her medical records. It also fed trust concerns that a large number of voters have about Mrs Clinton.
She was expected to be back on the campaign trail yesterday, after a three-day break, cancelling trips to California and Nevada.
She will deliver speeches in the coming days on the economy and national service, her campaign said.
But Mrs Clinton returns to polling figures that show Mr Trump holding a narrow lead in key battleground states Ohio and Florida.
According to a CNN/ORC poll released on Wednesday, in a four-way race in Ohio, Mr Trump would get 46 per cent of the vote to Mrs Clinton's 41 per cent. Libertarian Party candidate Gary Johnson has 8 per cent, while Green Party nominee Jill Stein trails with 2 per cent.
In Florida, Mr Trump leads with 47 per cent, compared with Mrs Clinton's 44 per cent. Mr Johnson takes 6 per cent of the vote, while Dr Stein manages just 1 per cent.
White voters seem to be giving Mr Trump the edge in both states, while Mrs Clinton still has overwhelming support from non-white voters.
Calls for more detailed medical records from the two candidates resulted in Mr Trump sharing a letter summarising the results of his latest physical examination conducted last week at a taping of daytime television programme The Dr Oz Show on Wednesday.
Audience members said Mr Trump, 70, revealed he had been taking regular doses of a statin, a class of drug that lowers cholesterol, and hopes to lose some weight, though he does not exercise regularly.
The property tycoon, who would be the oldest president ever elected if he wins in November, also discussed the need for openness on both candidates' medical records.
The Clinton campaign released a letter from her doctor detailing the "mild pneumonia" she suffered last week. The letter stated that Mrs Clinton was diagnosed with "a mild non-contagious bacterial pneumonia" last Friday and "treated with antibiotics for pneumonia and advised to rest".
"My overall impression is that Mrs Clinton has remained healthy and has not developed new medical conditions this year other than a sinus and ear infection and her recently diagnosed pneumonia," wrote Dr Lisa Bardack, Mrs Clinton's physician. "She continues to remain healthy and fit to serve as president of the United States."
The last public disclosure on the state of her health was more than a year ago - last July - when Dr Bardack's two-page letter described her as a "healthy female with hypothyroidism and seasonal allergies".
The Trump campaign yesterday released a doctor's letter saying its candidate is in "excellent physical health".