HARRISBURG, Pa. (AP) — A bitter dispute broke out on the floor of the Pennsylvania Senate on Tuesday when majority Republicans blocked a Democratic incumbent from being sworn in because his GOP challenger has disputed the razor-thin election results.

Lawmakers were back in the Capitol for swearing-in day, facing a still-raging pandemic and a massive budget gap. Republicans hold large majorities in both chambers.

The Senate quickly dissolved into chaos over the status of Democratic Sen. Jim Brewster of Allegheny County.

Democrats in the Senate began protesting — in some cases, shouting — after the GOP refused to seat Brewster, whose election was certified by the state but is being contested by his Republican challenger, Nicole Ziccarelli.

Republicans then voted on a motion to remove Lt. Gov. John Fetterman, a Democrat, as the presiding officer, after Fetterman insisted that Brewster be seated with the other senators. They then voted through another motion to recognize the election in every Senate contest, except for Brewster’s.

Republicans have not said how long they will take to review Ziccarelli’s election challenge before voting on it, or how long the GOP majority is willing to leave the seat vacant. The open seat does not affect the balance of power in the Senate, where Republicans hold 28 of 50 seats.

When it came time for newly elected and reelected Senate Democrats to take the oath of office, Brewster stepped aside to defuse what had been shaping up as a standoff. Fetterman subsequently left the chamber.

“I had no desire to ruin picture day,” Fetterman said afterward. “It came down to, there’s got to be a way for both sides to maintain their dignity and we can find a way forward. Unfortunately, that wasn't the case.”

The state House begins the session with 113 Republican seats and 90 Democratic, although one of those GOP districts is vacant because of the death on Saturday of Westmoreland County Rep. Mike Reese. The House held a brief condolence ceremony for Reese.

The House swore in its members in four groups to limit potential coronavirus exposure. Each chamber's operating rules will also be considered, and House Democrats want mask wearing to be mandatory during floor sessions and committee meetings.

Only a few House Republicans did not wear masks to take their oath of office.

Republican draft rules do not address the mask issue, which could be taken up by a bipartisan group of House leaders that manages chamber operations.

The Senate voted 31-18, largely on party lines, to make Centre County Republican Sen. Jake Corman its presiding officer, president pro tempore. The House is expected to elect Lancaster County Republican Rep. Bryan Cutler as speaker.

The session brings the first woman to be majority leader in the Senate, Republican Sen. Kim Ward of Westmoreland County, and the first woman and first African American to be a floor leader in the House, Minority Leader Joanna McClinton, D-Philadelphia.

Legislators this year will have to figure out how to redraw congressional district lines based on new census results that are expected to cut one member of Congress from Pennsylvania's 18-member delegation.

Later this year, the four caucus leaders will also begin redrawing General Assembly lines with participation from a fifth member they can select. If they remain deadlocked on the fifth member, as is likely, the Democratic-majority state Supreme Court will chose the tie-breaking member for them.