Washinton CNN  — 

Republican Sen. Chuck Grassley of Iowa, who is 87 years old, tweeted Tuesday that he tested positive for Covid-19 on Tuesday, after saying earlier he would self isolate after a possible exposure.

“I’ve tested positive for coronavirus,” Grassley wrote. “I’ll (be) 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.”

Grassley, as president pro tempore, is the most senior Republican in the chamber, putting him in the presidential line of succession. He is the second-oldest member of the Senate, just a few months younger than Democratic Sen. Dianne Feinstein of California, who is also 87. The oldest member of the House, Republican Rep. Don Young of Alaska, is also 87 and tested positive for Covid-19 last week.

Grassley is the second GOP senator in under a week to announce that he’s isolating after a possible Covid exposure. Republican Sen. Rick Scott of Florida said Saturday that he was isolating as well after coming into “contact with someone who subsequently tested positive for COVID.” A handful of House members have also tested positive in the last week or are isolating.

Grassley’s absence had an immediate impact on Senate business. He missed Tuesday’s votes because of his quarantine, his first missed vote since 1993 when he missed due to floods in his state, according to his office. One of those missed votes Tuesday included attempting to break a filibuster for the confirmation of Judy Shelton, President Donald Trump’s controversial nominee for the Federal Reserve. Republicans failed to get enough votes to advance the nomination, though Senate Majority Leader Mitch McConnell could bring the vote up again in the near future.

It’s unclear which if any senators who interacted with Grassley on Monday would isolate themselves. Republican Sen. Roy Blunt, a member of GOP leadership, said Grassley attended their Republican leadership meeting Monday. Asked if any who attended the meeting will quarantine, Blunt, who chairs the Senate Rules Committee, told reporters: “You’d have to ask them.”

He added, “I was like, 12 feet away from him at the meeting that’s why we’re in that big room.”

“We are all spread out,” GOP Sen. John Barrasso of Wyoming told CNN of the leadership meeting. Republican Sen. Rob Portman of Ohio, who attended Monday’s leadership meeting, said they were wearing masks.

On whether there are any other precautions being taken, as Grassley presided over the Senate floor on Monday and attended meetings, Blunt said Tuesday: “He did. He did. And he’s been great about wearing his mask and I think great about taking care of himself, and so I think he’s done everything he can … does everything he could be expected to do to protect himself and the rest of us. People catch this.”

“Not that I know of,” Barrasso, who is also in GOP leadership, told CNN when asked if they will have to take extra precautions now that Grassley tested positive.

Grassley was seen at the Capitol speaking to reporters Monday afternoon.

The threat of coronavirus has been a consistent influence over leaders from both parties and chambers of Congress since the pandemic began, and how lawmakers react has been under increased scrutiny amid the latest wave of cases sweeping the country.

At least two members of the US House of Representatives announced Monday they tested positive for Covid-19 and another member announced he was isolating after possibly being exposed, a sign of the looming threat of coronavirus on Capitol Hill. Colorado Rep. Ed Perlmutter, a Democrat, announced Tuesday that he had tested positive for the virus and was isolating.

“I learned today that I have tested positive for COVID-19. As of now, I am asymptomatic and I’m feeling good. I am currently in Washington D.C. and plan to isolate in my apartment while continuing to work and voting remotely,” he said in a statement.

Grassley’s announcement also comes a day after a dispute on the Senate floor when Ohio Democratic Sen. Sherrod Brown was recognized by Alaskan GOP Sen. Dan Sullivan and asked Sullivan to put on a face mask.

“I’d start by asking the presiding officer to please wear a mask as he speaks and people below him are — I can’t tell you what to do,” Brown said, referring to Sullivan.

“I don’t wear a mask when I’m speaking, like most senators,” Sullivan responded.

Brown responded angrily: “I know you don’t need my instruction, but there clearly isn’t much interest in this body in public health. We have a president who hasn’t shown up at the coronavirus task force meeting in months. We have a majority leader that calls us back here to vote on an unqualified nominee, and at the same time to vote for judge after judge after judge, exposing all the people who can’t say anything, I understand, the people in front of you, and the presiding officer, and expose all the staff here, and the Majority Leader just doesn’t seem to care.”

This story has been updated with additional developments Wednesday.

CNN’s Manu Raju and Ali Zaslav contributed to this report.