AUGUSTA — Olympia Snowe’s surprise announcement that she will retire from the U.S. Senate set off intense speculation Tuesday about who will run for her seat and what the ripple effects will be on Maine’s two U.S. House races.

While Democrats expressed excitement about the new possibilities for 2012, Republicans were clearly disappointed. Members of her party were blindsided, a little more than two weeks before the filing deadline for Maine’s June 12 primaries.

“The ink hasn’t dried off her announcement (to run),” said Josh Tardy, a former House GOP leader who now works as a lobbyist. “On all sides, it blows (the race) wide open. The Democrats may take another focus on it and increase their field. It will create a frenzy on the Republican side.”

Democratic leaders cited Snowe’s service to the state even as they considered the impact of her departure.

House Minority Leader Emily Cain, D-Orono, who praised Snowe as “a powerful role model for women around our nation and around the world,” said Democrats have three strong candidates, and there may soon be more.

“With someone who has served as long as Olympia Snowe has, there are many doors that open when an announcement like this comes,” she said.

The Democrats now have four declared candidates: state Sen. Cynthia Dill of Cape Elizabeth; state Rep. Jon Hinck of Portland; Matthew Dunlap, a former legislator and secretary of state from Old Town; and Benjamin Pollard, a home builder from Portland.

Snowe had one GOP primary challenger, Scott D’Amboise of Lisbon Falls. D’Amboise issued a statement Tuesday saying he is the presumptive GOP nominee because there is so little time for other candidates to qualify.

“I respect Senator Snowe’s decision, and look forward to facing the Democratic nominee in the fall,” he said.

A candidate needs 2,000 certified signatures by March 15 to qualify for the primary ballot. But all observers now expect the field to grow and shift.

Rep. Chellie Pingree, D-1st Congressional District, thanked Snowe for her service and said she is considering a run for the seat.

Pingree’s husband, S. Donald Sussman, is a financier, philanthropist and frequent Democratic donor who recently purchased a 5 percent equity stake in MaineToday Media through Maine Values LLC.

MaineToday Media owns and operates The Portland Press Herald/Maine Sunday Telegram, the Kennebec Journal in Augusta, the Morning Sentinel in Waterville and other media outlets in Maine.

Democratic Rep. Mike Michaud, who represents Maine’s 2nd Congressional District, also praised Snowe and said he, too, is considering a run.

A decision by Michaud or Pingree – or both – to run for Senate would create a scramble for one or both House seats.

Maine Senate President Kevin Raye, R-Perry, who was an aide to Snowe for more than 17 years, said he will consider a run for the Senate seat. Raye is now running for the 2nd District congressional seat.

Other Republicans mentioned as possible candidates Tuesday were Secretary of State Charlie Summers and former ambassador and gubernatorial candidate Peter Cianchette.

Eliot Cutler of Cape Elizabeth, an independent who narrowly lost Maine’s governor’s race in 2010, also was widely mentioned as a possible candidate.

“I think we’re looking at a whole new race now,” said Ron Schmidt, associate professor of political science at the University of Southern Maine in Portland.

Schmidt said he was amazed by Snowe’s decision, which draws national attention to Maine’s Senate race.

With Snowe running, the seat was considered safe for the GOP, Schmidt said. Now, it is much more of a toss-up.

“I would have said, before, there were five, or at top seven, Senate seats in play (nationwide). This makes another one,” he said.

In most of the other competitive Senate races, Democrats are trying to hold seats. “Here, all of a sudden, they have a chance to pick one up,” Schmidt said.

Maine’s political parties will have to sort out quickly who will run for what.

“It opens up a lot of opportunity for people,” said state Senate Majority Leader Jonathan Courtney, R-Springvale.

Courtney decided earlier this year against a run for the 1st Congressional District seat. He said Tuesday he was not prepared to say whether he will run for U.S. Senate. He said he expects a lot of interest on the Republican side.

“It’s a U.S. Senate seat,” he said. “Washington is clearly broken. You look at the approval ratings for members of Congress and it’s in the single digits. We need a new approach.”

Republican Party Chairman Charlie Webster said he had spoken to Snowe about her frustration. “She’s always been a consensus builder,” he said.

Webster said he did not know who would step in, but the party has a “farm team” of good candidates. “It’s going to be an interesting couple of weeks,” he said.

Lizzy Reinholt, a spokeswoman for the Maine Democratic Party, said many are considering a run. “I think, in the next few days, we’re going to see quite a few names come forward.”

Hinck, the Democratic state representative already running for the seat, said he understands Snowe’s frustration.

“I’ve often thought it seems to me she must be in an untenable position. The word ‘moderate’ (to describe Snowe) is accurate, in my opinion.” But, he said, “her party has become increasingly extreme.”

Hinck said he and others who already are in the race have an advantage.

“The people who would be willing to stand up to run against Olympia Snowe, the titan, have already demonstrated their mettle,” he said.

Dill, the Democratic state senator running for Snowe’s seat, said, “I’m thrilled that, finally, there’s a realistic opportunity to make some different choices for Maine in the U.S. Senate. … I’m pleased, like so many of Maine’s leaders, (Snowe) is exiting on a graceful note.”

Gov. Paul LePage issued a statement Tuesday thanking Snowe for her service.

“I was saddened to learn today that Senator Olympia J. Snowe will not seek re-election for United States Senate,” he said. “Senator Snowe has represented the State of Maine for more than three decades with integrity and has been a tremendous leader and a tireless advocate for the people of Maine.”

MaineToday Media State House Writer John Richardson can be contacted at 620-7016 or at: jrichardson@mainetoday.com

MaineToday Media State House Writer Susan Cover can be contacted at 620-7015 or at: scover@mainetoday.com