Sen. Brain Schatz (D-Hawaii) announced on Thursday that he tested positive for COVID-19 this week, a development which could slow down the Democrats’ renewed push for voting rights reform.

Schatz, who is fully vaccinated and boosted, said he is asymptomatic and is isolating at home. He said he expects to be back to work “soon.”

“Earlier this week, I tested positive with a breakthrough case of COVID-19. Thankfully, I am fully vaccinated, boosted, and asymptomatic. I have been following CDC guidelines and isolating at home. I am in consultation with the Office of the Attending Physician, and expect to be back soon,” Schatz wrote in a statement.

The news of Schatz’s breakthrough case comes amid a concerted push from President Biden and Democratic leaders for election reform and to change Senate rules on the legislative filibuster to pass the legislation. 

Senate Majority Leader Charles Schumer (D-N.Y.) has said that if Senate Republicans again block voting rights reform, he will move to change Senate rules by Jan. 17.

The Senate requires 50 votes to change rules, which means Schatz’s positive COVID-19 test and absence from the Capitol puts the Democrats’ push in jeopardy.

Aside from Schatz’s absence, however, the Democratic caucus faces hurdles for changing Senate rules to approve voting rights legislation. Sen. Kyrsten Sinema (D-Ariz.) reiterated her support for the filibuster Thursday, effectively dashing Democrats hopes of reform. 

Sen. Joe Manchin (D-W.Va.) has also previously said he is against changing Senate rules to pass voting rights legislation. 

Manchin on Thursday told reporters Sinema’s speech was “excellent,” adding, “I think it’s the points that I’ve been making for an awful long time and she has too.”

A number of congressional lawmakers have tested positive for COVID-19 breakthrough cases in recent weeks, including Reps. Michael McCaul (R-Texas) and Alexandria Ocasio-Cortez (D-N.Y.).

Capitol physician Brian Monahan revealed last week that the seven-day average positivity rate in the U.S. Capitol had increased from less than 1 percent to more than 13 percent. The majority of cases have been detected in vaccinated individuals.

New infections have increased nationwide as the U.S. grapples with the highly transmissible omicron variant. Early reports, however, suggest that the new variant causes less severe illness in vaccinated individuals.

The Centers for Disease Control and Prevention (CDC) says that while breakthrough cases are “expected,” they typically cause less severe illness compared to infections among unvaccinated individuals.