NEWTON, Iowa — Bernie Sanders had to reassure a concerned Democrat that he was in good health during a town hall in Iowa.

"My health is great," Sanders said in Newton, Iowa, in response to the supporter.

The Vermont senator, 78, suffered a heart attack last October while on the campaign trail in Las Vegas and quickly received two stents to fix a blocked artery. On Saturday, he said the care he was given at Desert Springs Hospital Medical Center made him "appreciate that not everybody would get that same quality of care."

Following the release of a new CNN/Des Moines Register poll that showed him leading a tight four-way race in the first-in-the-nation state, Sanders described his final push before the Iowa caucuses on Feb. 3 as "vigorous."

“I would not be here asking for your support if I did not believe I had the strength to run this campaign,” he said.

Sanders is the oldest presidential primary candidate vying for the 2020 Democratic nomination. If he makes it to the White House, he would be the oldest president ever to serve in office.

Last week, his team disclosed four pages of doctors' notes documenting his medical history. He had earlier suggested he would "probably not" provide more details about his health before caucusgoers gather next month.