Chuck Grassley, the oldest Republican US senator and the president pro tempore of the chamber, announced he tested positive for the coronavirus on Tuesday.

He previously announced he was in quarantine after having a close contact with someone who tested positive for the virus.

“I’ve tested positive for coronavirus,” Grassley tweeted. “I’ll b (sic) following my doctors’ orders/CDC guidelines & continue to quarantine. I’m feeling good + will keep up on my work for the ppl of Iowa from home. I appreciate everyone’s well wishes + prayers &look fwd to resuming my normal schedule soon.”

Being the president pro tempore of the US Senate, Grassley is third in the presidential line of succession, behind Vice President Mike Pence and House Speaker Nancy Pelosi.

Grassley, 87, who represents Iowa, has the second-longest tenure in the US Senate as he was first elected to the body in 1980.

His age puts Grassley at a higher risk of complications from the coronavirus than the general population.