Sen. Bernie Sanders (I-VT) had an emergency procedure to fix a blocked artery after experiencing chest pain Tuesday night, according to his campaign, and is recovering in Las Vegas, Nevada, where he was on the presidential campaign trail.

“During a campaign event yesterday evening, Sen. Sanders experienced some chest discomfort,” Jeff Weaver, a senior adviser on the campaign, said in a statement. “Following medical evaluation and testing he was found to have a blockage in one artery and two stents were successfully inserted. Sen. Sanders is conversing and in good spirits.”

Sanders was on a swing through Nevada, a crucial early state where recent polls have shown him tied for first place with former Vice President Joe Biden. His campaign has canceled events and appearances until Sanders recovers. The senator was originally scheduled to attend three events in Las Vegas Wednesday: a presidential forum on gun safety; a town hall on his plans to erase medical debt, pass single-payer Medicare-for-all health care, and expand Social Security; and a community meeting with a local lawmaker.

Sanders was asked about his health just last week during an appearance Stephen Colbert’s late night talk show.

“I’m in good health and running a vigorous campaign,” he said then, knocking on Colbert’s desk.

The 78-year-old senator has been on a relentless campaign schedule, with upward of four, or often more events a day in early primary states. His campaign announced the biggest fundraising haul of the Democratic presidential race, so far, this week: $25 million in donations between July and the end of September, followed by announcing a $1.3 million television buy in Iowa. The campaign has postponed the ad buy, Sanders spokesperson Sarah Ford told Vox.

Several of Sanders’s 2020 rivals quickly tweeted well-wishes, including Biden and fellow Sens. Kamala Harris, Cory Booker, and Elizabeth Warren.