WASHINGTON (AP) — Iowa Sen. Chuck Grassley, the longest-serving Republican senator and third in the line of presidential succession, said he has tested positive for the coronavirus.

Grassley, 87, had announced earlier Tuesday that he was quarantining after being exposed to the virus and was waiting for test results. On Tuesday evening, he tweeted that he had tested positive.

“I'll b 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," he tweeted.

Grassley said he looks forward to “resuming my normal schedule soon.”

The Iowa Republican, who was in the Senate and voting on Monday, did not say how he had been exposed. His office said that he was not experiencing any symptoms and was isolating in his Virginia home.

The announcement from one of the Senate's most prominent members — and one of its oldest — underscored concerns across the Capitol about the safety of lawmakers, staff and other workers in the sprawling complex as cases have spiked across the country and members have traveled back and forth from their states. At least three members of the House have tested positive in the last week, and several more are quarantining.

The increase in cases also threatens the progress of legislation and other work as the Republican Senate, in particular, tries to wrap up business in the remaining weeks of President Donald Trump's term. Grassley's absence on Tuesday helped Democrats block the nomination of Judy Shelton, Trump’s controversial pick for the Federal Reserve. Republican Sen. Rick Scott of Florida was also absent as he is in quarantine after an exposure.

Grassley is the president pro tempore of the Senate, meaning he presides over the chamber in the absence of Vice President Mike Pence and is third in line for the presidency, behind Pence and House Speaker Nancy Pelosi. The president pro tempore is the senator in the majority party who has served the longest, and Grassley has been a senator for 40 years.

As pro tempore, Grassley opens the Senate each day. He did so on Monday, leading the Pledge of Allegiance alongside others on the floor and then giving remarks without wearing a mask. He also joined other senators on the floor later Monday evening for a procedural vote on a federal judge, that time wearing a mask but speaking to several senators at close distance.

In his remarks, Grassley said it was “more important than ever to stop the surge" of the virus around the country and the world.

“This virus is hitting rural and urban areas alike,” Grassley said. “No community is immune. I ask every Iowan to continue to do their part to keep their family and neighbors safe."

Although he was not wearing a mask while he spoke, Grassley encouraged Americans to “wash your hands, limit your activity outside your household, social distance, wear a mask.”

Grassley also attended leadership meetings with other Republican senators on Monday, according to Missouri Sen. Roy Blunt, another member of GOP leadership. Blunt told reporters Tuesday evening that he “was like 12 feet away” from Grassley in the meeting, which he said was in a large room.

Blunt said Grassley “has been great about wearing his mask, and I think great about taking care of himself, so I think he’s done everything he can.”

While most members of the Senate have consistently worn masks in hallways and meetings, members of both parties often take them off when the cameras are on — either on the Senate floor or when talking to press. Senate Majority Leader Mitch McConnell and Senate Democratic leader Chuck Schumer also took their masks off when speaking on the Senate floor Monday.

Still, some Democratic members have started to push back on that practice. Sen. Sherrod Brown, D-Ohio, interrupted a floor speech Monday afternoon to ask Sen. Dan Sullivan, R-Alaska, to put on his mask as he presided over the Senate, noting that he could be exposing staff nearby.

“I don't wear a mask when I am speaking, like most senators,” Sullivan responded, snapping that he would put the mask on but that “I don't need your instruction.”

After the exchange, Texas Sen. Ted Cruz tweeted his support for Sullivan, saying that Brown was being “a complete ass" and that his request of the Alaskan was “an ostentatious sign of fake virtue.”

A spokesperson for McConnell did not return a request for comment on whether he would encourage testing for senators who may have come into contact with Grassley. McConnell has maintained that regular testing is not needed in the Senate, though the Capitol physician announced this week that there would be testing available for members of the House and their staff who had recently traveled to Washington.

Grassley's announcement comes as the longest-serving Republican in the House, Alaska Rep. Don Young, said he was recovering from the coronavirus. In a statement Monday, Young said he had been hospitalized and “I had not felt this sick in a very long time.”

Young, also 87, said he had been discharged and is now “on the road to recovery.”

By missing votes Tuesday, Grassley broke a 27-year streak of not missing a single Senate vote. According to his office, the last time he missed a vote was in 1993, when he was in Iowa assisting with relief efforts after severe flooding.

He said in a statement Tuesday that he had voted 8,927 times without skipping a vote — a record in the Senate.

“I’m disappointed I wasn’t able to vote today in the Senate, but the health of others is more important than any record,” he said.

Grassley was first elected to the U.S. House in 1974 and then to the Senate in 1980. He is chair of the Senate Finance Committee and is expected to become the top Republican on the Senate Judiciary Committee when a new Senate session begins in January.