Presidential hopeful Bernie Sanders on Wednesday canceled all appearances until further notice after the 78-year-old senator underwent a procedure for an artery blockage.

In a statement, the campaign advisor Jeff Weaver said Sanders "experienced some chest discomfort" during an event Tuesday. Tests found a "blockage in one artery," and Sanders had two stents inserted, he said.

"Sen. Sanders is conversing and in good spirits. He will be resting up over the next few days," Weaver said. "We are canceling his events and appearances until further notice, and we will continue to provide appropriate updates."

In a tweet later Wednesday, Sanders said he is "feeling good." He used his situation to make the case for government-run universal health care, his signature campaign policy.

The tweet from Sanders' campaign account said, "None of us know when a medical emergency might affect us. And no one should fear going bankrupt if it occurs. Medicare for All!"

Bernie Sanders tweet

Sanders is the oldest presidential candidate seeking to challenge President Donald Trump in 2020. The Vermont independent is two years older than former Vice President Joe Biden, who has led most national and state primary polls despite concerns about his mental sharpness.