Maine’s third big-name Democrat to consider running for the U.S. Senate, former Gov. John Baldacci, expects to take his time to announce any decision because, for now, his Pentagon job poses an obstacle to any candidacy.

Baldacci, 57, is prohibited from politicking while he completes a Pentagon contract this month, preventing any announcement about whether he’ll enter the race, which was thrown open by Sen. Olympia Snowe’s announcement last week that she won’t seek a fourth term.

In a little more than a week, U.S. Reps. Mike Michaud and Chellie Pingree considered running and then bowed out to focus on defending their House seats.

Baldacci hadn’t made up his mind as of Thursday, and couldn’t talk about it publicly even if he had decided, said his spokesman, Dan Cashman.

Behind the scenes, petition signatures were being collected for Baldacci. The nomination petitions could be submitted before the March 15 deadline to appear on the June 12 primary ballot.

If he runs, Baldacci will be a strong candidate, having been elected twice as governor and three times to the U.S. House, Cashman said.

“Gov. John Baldacci has a pretty successful record when it comes to running a campaign,” he said.

Snowe’s announcement set off a scramble because potential candidates for the soon-to-be empty seat face the March 15 deadline to submit at least 2,000 signatures to get on the primary ballot.

Michaud expressed interest in the seat before announcing 48 hours later that he would stick to Maine’s 2nd Congressional District. Pingree followed suit on Wednesday, deciding to run again in the 1st District after former independent Gov. Angus King Jr. announced that he was running.

Democrats have a tough choice because they could end up splitting the vote with King, giving a boost to the Republican in the race. That’s what happened when Republican Gov. Paul LePage won a three-way race in 2010, with 39 percent to 37 percent for independent Eliot Cutler.

Like Cutler, King is a former Democrat.

“It’s a catch-22 for the Democrats because if they run a strong candidate, they run a risk of losing the election. If they run a token candidate, they put their faith in Angus King caucusing with them,” said Michael Franz, professor of government at Bowdoin College in Brunswick.

Four previously announced Democrats remain in the Senate race: former Secretary of State Matthew Dunlap, state Rep. John Hinck, state Sen. Cynthia Dill and home builder Ben Pollard.

Dunlap said he understands that candidates with greater name recognition, like Pingree and Michaud, had to give the race a look. For now, he said, he intends to stay in the race regardless of Baldacci’s decision. He said he’s at peace with the changing field.

“All we can do is push forward on the campaign. You can’t wait to see what others are going to do. I’m committed to getting down there and making a difference,” Dunlap said.

On the Republican side, Scott D’Amboise could be joined by state Treasurer Bruce Poliquin, Attorney General William Schneider, Secretary of State Charles Summers, state Sen. Debra Plowman and former state Sen. Rick Bennett, all of whom have expressed interest.