HOUSTON ― Joe Biden on Thursday committed to releasing his medical records before the first votes are cast in the battle for the Democratic presidential nomination.

The 76-year-old former vice president pledged to do so when asked by HuffPost about concerns ― raised by some of his challengers in the Democratic race ― about his fitness for office.

“What the hell concerns?” Biden said in a brief comments following a meet-and-greet with students at Texas Southern University in Houston, site of last night’s debate among 10 Democratic White House contenders. He then jokingly challenged a reporter to a wrestling match. (Full disclosure: It was me.)

He added he would release the records “when I get the next physical ... before there’s a first vote.”

The Iowa caucuses kick off the balloting in the Democratic race on Feb. 3.

Biden’s promise Friday was new. Previously he had said only that he would release his records before the general election.

At one point in Thursday’s debate, former Housing Secretary Julián Castro targeted the former vice president with a sharp attack, suggesting that Biden’s memory was failing him. Biden’s campaign called the barb a “cheap shot,” and that characterization has been echoed by others in the media.

But New Jersey Sen. Cory Booker seemed to back up Castro in a post-debate interview with CNN, saying, “There’s a lot of people concerned about Joe Biden’s ability to carry the ball all the way across the end line without fumbling.”

Though Biden consistently has led the polls in the Democratic race, periodic verbal gaffes and miscues he’s committed have opened the gate to questions about his mental alertness.

Biden hasn’t disclosed his medical history since 2008, when he last sought the presidency and ended up as Barack Obama’s running mate on the winning Democratic ticket. At that time, doctors disclosed he suffered from an irregular heartbeat as recently as 2006. The records also showed he took aspirin and was prescribed medication to help lower his cholesterol.

This is a developing story. Check back for more updates.