ST. PAUL — A Minnesota resident sued Friday to force the state’s new lieutenant governor out of the state Senate seat she aims to keep, arguing it’s unconstitutional for longtime Republican lawmaker Michelle Fischbach to hold two offices.

Fischback was elevated to the role of lieutenant governor as part of a chain reaction after Al Franken resigned from the U.S. Senate amid allegations of sexual misconduct. Democratic Gov. Mark Dayton appointed his second-in-command, Tina Smith, to Franken’s seat; as president of the state Senate, Fischbach then automatically assumed Smith’s old job. But with Republicans guarding a narrow majority in the state Senate, Fischbach made clear she did not want the lieutenant governor job and said she would keep her central Minnesota Senate seat. Democrats balked and promised to sue.

Destiny Dusosky, a constituent in Fischbach’s heavily Republican Senate district who chaired the local Democratic Party chapter last year, filed suit in Ramsey County District Court.

The lawsuit says the state constitution makes clear that someone can’t hold two offices simultaneously and asks the court to force Fischbach from the Senate seat. It argues that Dusosky “will be deprived of representation in the Minnesota Senate due to now-lieutenant governor Fischbach’s attempt to continue to hold the office of state Senate.”

Republican Senate Majority Leader Paul Gazelka called the lawsuit “disappointing, but not surprising.”

“This disappointing lawsuit is simply political maneuvering by Democrats to try to change the outcome of the 2016 election,” Gazelka said in a statement.

Fischbach officially ascended to become lieutenant governor Jan. 3, when Smith was sworn in as a U.S. senator. But Fischbach has not scheduled an oath of office for the new job.

Republicans have fought to protect her spot in the Senate, pointing to an 1898 Supreme Court ruling that condoned a lieutenant governor maintaining his role in the Senate. And Gazelka tried to organize a special legislative session to elevate a Democrat to take the job in Dayton’s administration instead, but Democrats shut it down.

Friday’s lawsuit echoes weeks of Democratic protests, noting that a 1972 constitutional amendment severed the lieutenant governor’s previous role as presiding officer of the Senate. It also references a case similar to Fischbach’s in 1976, when a state senator was forced to resign as he ascended to become lieutenant governor.

Dusosky’s attorney, Charlie Nauen, said he wasn’t sure whether the case could be fast-tracked for resolution in the state Supreme Court but hoped it would be resolved before the Legislature’s Feb. 20 return.

Fischbach’s removal would trigger a special election with potentially high stakes. Republicans hold a 34-32 majority, but the margin could change after a Feb. 12 election to replace former Sen. Dan Schoen, a Democratic lawmaker who resigned last year after several allegations of sexual harassment.

If Democrats win that election, a contest for Fischbach’s seat gives them a shot at the majority. Fischbach has promised to run again if she’s forced out.