Senator Joe Manchin, the West Virginia Democrat who has thwarted many of Joe Biden’s most ambitious policy goals, has tested positive for Covid.

The 74-year-old senator is fully vaccinated and said on Twitter on Monday he was experiencing mild symptoms.

Manchin’s positive diagnosis comes as Biden himself is recovering from Covid-19. After four days of taking the antiviral Paxlovid medication, the president’s symptoms from the virus “have now almost completely resolved”, his physician, Kevin O’Connor, said in a statement on Monday. “When questioned, at this point he only notes some residual nasal congestion and minimal hoarseness.”

Both men tested positive amid a surge in Covid cases across the US in recent weeks. The highly contagious BA.5 subvariant, which can avoid immunity from vaccines better than its predecessors, is now the dominant strain of the virus in the US.

Manchin’s diagnosis could affect an expected vote this week on increasing semiconductor chip production in the US, the Associated Press reported. While members of the US House of Representatives can vote remotely by proxy, members of the Senate cannot.

Manchin dealt a significant blow to Democrats earlier this month when he said he would not support climate change and tax provisions in a bill Biden hoped would be a signature part of his domestic agenda.