PORTLAND — Four big Republicans have taken out nominating papers to run for the U.S. Senate in hopes of replacing Olympia Snowe.

Maine Attorney General Bill Schneider, Maine Secretary of State Charles Summers, State Treasurer Bruce Poliquin and ex-Maine Senate President Rick Bennett each took out papers early Friday afternoon, said Megan Sanborn, a spokeswoman for the secretary of state’s office.

Assistant Maine Senate Majority Leader Deb Plowman, another Republican, said Friday she is also thinking about jumping into the race.

Plowman had already taken out papers to run against U.S. Rep. Mike Michaud, D-Maine, in the 2nd District. But she appears to be reconsidering after Maine Senate President Kevin Raye opted against a Senate run to also try to win the 2nd District.

Before all of Friday’s big announcements, Scott D’Amboise of Lisbon Falls was the only Republican candidate who was running for Snowe’s seat.

Snowe, a Republican, announced Tuesday she wouldn’t seek a fourth term, citing increasing frustration with unbreakable partisanship in Congress.

Her late-in-the-game announcement shocked the state’s political foundations, and created a free-for-all for candidates who finally have hope of winning the seat.

On the Democratic side, Rep. Chellie Pingree, D-Maine, has said she’s seriously considering a run  and has taken out nominating papers, but isn’t expect to announce her final decision until next week.

Former Gov. John Baldacci has also taken out papers.

And U.S. Rep. Michael Michaud, D-Maine, took out papers Wednesday, but said last night that he has instead decided to run for re-election for his 2nd District House seat.

Candidates for the Senate have until March 15 to turn in petitions with at least 2,000 signatures for a spot in the primaries, which will be held in June.

Pingree’s husband, S. Donald Sussman, is a financier and philanthropist who recently purchased a 5 percent equity stake in MaineToday Media, which owns and operates The Portland Press Herald, the Kennebec Journal in Augusta and the Morning Sentinel in Waterville.