BREAKING: Mike Michaud has announced that he won’t run for the U.S. Senate this year. A new story will follow.

AUGUSTA, Maine — While three of Maine’s biggest Democratic names wasted little time in taking the first step to run for the U.S. Senate, state Republicans appear to be exercising caution.

Representatives for former two-term Gov. John Baldacci and sitting U.S. House members Chellie Pingree and Mike Michaud all secured petition papers from the Secretary of State’s Office on Wednesday — one day after U.S. Sen Olympia Snowe announced she would not seek a fourth term.

Many top-tier GOP names are being discussed but they have not officially begun gathering signatures as of late Thursday, according to elections officials. Neither have prominent independents such as former Gov. Angus King or Eliot Cutler.

Party candidates only have until March 15 to turn in 2,000 signatures to run for the seat unexpectedly being given up by Snowe.

So what are Republicans waiting for?

“Republicans are more thoughtful in our policies and our politics,” said Brent Littlefield, a GOP strategist and a senior adviser to Gov. Paul LePage.

University of Maine political scientist Mark Brewer said there is more to it than that.

“For the three big-name Democrats, they are all top-tier candidates. There isn’t anyone on the Republican side with that kind of resume,” Brewer said. “I think part of the reason why all three [Democrats] came out early was: they wanted to make it clear to voters and Democratic activists that they were all interested. For the Republicans, I think it makes sense for them to wait a little bit.”

One candidate, Scott D’Amboise, is in the Senate race already but the reality is that other Republicans could be gathering signatures quietly already.

Megan Sanborn, spokeswoman for the Secretary of State’s Office, said Thursday that candidates can request blank petitions or print petitions online and begin gathering signatures. In that instance, the secretary of state would not know the identity of a candidate until signatures are turned in.

“It’s certainly hard for us to know exactly who is gathering signatures at this point and we may not know until March 15,” Sanborn said.

That means the already long list of candidates for Senate, and also for Maine’s two U.S. House seats, could be even longer.

Party candidates for Senate have until March 15 to gather 2,000 valid signatures. House candidates need 1,000 signatures. Independents, however, don’t face the same tight deadline as major party candidates. For an independent to get on the general election ballot, he or she would need to gather 4,000 signatures by June 1.

Maine GOP Chairman Charlie Webster said his party’s leaders are having a lot of discussions about potential candidates but he wasn’t ready to identify anybody just yet.

“My opinion is that it will be a three-way race,” he said. “It will be one of the liberals and I think [former two-term independent Gov. Angus] King will run. That means we need to come to an agreement to bring someone that would be different than those two.”

Webster also said the Maine GOP is interested in more than just the Senate race. He said he expects either Pingree or Michaud to be the Democratic nominee, which would open up one of their House races.

A candidate cannot run for a House seat and Senate seat at the same time in Maine, according to Julie Flynn with the Secretary of State’s Office.

In other words, if Michaud and/or Pingree decide by March 15 to officially enter the Senate race, they would not be able to run for re-election in their House race should either lose in a Senate primary.

The prospect of Pingree, Michaud or both leaving their House seats has opened the floodgates for potential candidates in those districts.

“I’d be stunned if they enter into a primary together. I think one of those three emerges,” Brewer said of the top three Democrats. “I think Michaud’s the strongest. He’s popular in his district and I don’t think his lack of name recognition in the 1st District hurts him because he’s still a Democrat.

“A lot of people think Pingree is the front-runner, but I think she’s the weakest of the three. I can’t see her having an easy time getting support in the 2nd District.

“That puts Baldacci in the middle,” Brewer said. “He has a nice resume and he’s won a lot of campaigns but there are still some lingering negatives from his time as governor.”

Another question that has been posed is whether candidates who were gathering signatures to run for the Senate could use those same signatures to run for the House, or vice versa. Flynn said that’s not allowed.

That means someone such as Maine Senate President Kevin Raye, R-Perry, who has gathered the necessary signatures to run for the House, would have to start from scratch if he’s interested in running for the Senate.

Brewer said a candidate like Raye has more incentive to collect signatures quietly.

“If you’re Raye, you don’t want people to see that you’re doing something strategically,” he said.

The other big unknown is independent candidates, specifically King and Cutler, who finished a close second to Gov. Paul LePage in the 2010 gubernatorial election.

“I think King is stronger than Cutler,” Brewer said. “There are plenty of people who look back fondly on King and have wondered why he didn’t try to do something else.”