If Sen. Olympia Snowe is really retiring from the U.S. Senate because she can’t stand the poisonous partisanship in Congress – and we have no reason to doubt her word on that score – then Maine is paying a terrible price for the rancor that has become business as usual in Washington, D.C.

Snowe has been an outstanding senator, carrying on the tradition of conscientious public service established by a list of illustrious Mainers that includes Margaret Chase Smith, Ed Muskie and George Mitchell. She has enhanced that legacy, and her departure will leave a void that will be hard to fill.

Not everyone will mourn Snowe’s unexpected announcement that she will not seek re-election. Hard-core conservatives, especially those associated with the tea party movement, have been critical of her moderate views on some issues and her Senate voting record, which has consistently reflected her belief that she represents all the people of Maine, not just a narrow sector of the electorate or a rigid ideology that must be served at the expense of all other considerations.

Such ideology, of course, is a major cause of the legislative gridlock and political infighting that Snowe decried in announcing that she will leave the Senate in January after a congressional career that spanned 33 years in the House and Senate.

“As I have long said, what motivates me is producing results for those who have entrusted me to be their voice and their champion, and I am filled with that same sense of responsibility today as I was on my first day in the Maine House of Representatives,” Snowe said in a statement issued Tuesday. “I do find it frustrating, however, that an atmosphere of polarization and ‘my way or the highway’ ideologies has become pervasive in campaigns and in our governing institutions.”

Some might wonder if Snowe is truly fed up with the partisanship, or if she merely concluded that the rightward trend of Republican primary voters has undermined her chances of winning renomination. Our view: She’s truly fed up.

Snowe has no serious challenger in the primary, and there seems little doubt she could defeat any Democrat who might challenge her in the general election. The truth is, Washington’s partisan idiocy has worn her down.

Snowe met with the MaineToday Media editorial board a few months back and spent much of the meeting bemoaning the Senate’s inability – refusal? – to get things done. The institution often described as the world’s greatest deliberative body has simply broken down, Snowe said. No deliberating. No legislating. No meaningful work of any kind.

For a senator who has always prided herself on her willingness to deal in the Senate’s most cherished currency, principled compromise, her colleagues’ refusal to so much as consider compromise had turned the legislative process into an unnavigable sea of frustration and failure.

“With my Spartan ancestry I am a fighter at heart; and I am well prepared for the electoral battle, so that is not the issue,” Snowe said in her statement. “However, what I have had to consider is how productive an additional term would be. Unfortunately, I do not realistically expect the partisanship of recent years in the Senate to change in the short term.”

And so she decided to spare herself six more years of frustration.

We’re hard-pressed to blame her for throwing in the towel. But her decision is a devastating setback for the state of Maine. Her dedicated service to the state and its people will be sorely missed.