This summer's free performances of Shakespeare's ``The Tempest'' on the Boston Common - the first show kicks off tonight - are likely to be more than a critical success. They will mark a political triumph as well for Mayor Tom Menino's nemesis City Councilor Peggy Davis-Mullen.

By virtually anyone's reckoning, Shakespeare on the Common is Davis-Mullen's brainchild.

The idea was conceived at a City Hall reception in March 1996 when Davis-Mullen first met Steven Maler of the American Repertory Theater and Joan Moynagh, executive director of ARTS/Boston.

After the three had a follow-up lunch, Davis-Mullen attended a production of ``A Midsummer Night's Dream'' that Maler was directing. It was the first time she had ever seen Shakespeare performed. She was moved to tears.

Thus the notion of the Commonwealth Shakespeare Company was born.

Davis-Mullen persuaded Maler to allow ``A Midsummer Night's Dream'' to become the company's first production. She enlisted the help of the Parks Department to permit Copley Square to be used for the free performances. And then, most critically, she raised the money.

``I went through my Rolodex,'' says Davis-Mullen, ``calling everyone I could think of.''

Some $62,000 later, the play opened in July 1996 to wide acclaim for a four-night stint.

Now in its fifth year, the Commonwealth Shakespeare Company is virtually a Boston institution, the kind of thing one sees pictured on travel brochures. It has expanded its reach as well, running theater programs for kids in Boston neighborhoods such as Charlestown.

Davis-Mullen, Maler and Moynagh are still the mainstays behind the effort. Budgeted at $450,000, this year's production will cost seven times as much as ``Midsummer Night's Dream.'' It runs through Aug. 13 for a total of 24 performances. The lead roles are played by some of the area's best known actors and the elaborate staging and costuming are as good as any professional performance fetching $100 a seat.

Last year's successful run of ``Julius Caesar'' drew audiences of roughly 2,000 a night. Crowds for ``The Tempest'' are expected to be even larger, so much so, in fact, that the company, thanks to an anonymous donor, is spending an additional $40,000 on its sound system.

And it's still free.

Behind it all has been Davis-Mullen. Maler directs the plays while Moynagh is the company's producer. But it is Davis-Mullen who personally raises the money and pushes each year's performances forward.

There's an important subtext to this story, however. Not surprisingly, it's political.

Davis-Mullen is to politics what a lightening rod is to thunderstorms. She provokes strong reaction, pro and con. This is the woman, after all, who received a week's worth of press scrutiny just because she moved to West Roxbury.

She is also Menino's most persistent critic.

Considered one of his most likely opponents in 2001's mayoral race, the two are at such odds that there's almost a knee-jerk, I'll-do-the-opposite-of-whatever-you-do dynamic to their politics.Davis-Mullen loses no opportunity to knock Menino. For his part, Menino is delighted to see Davis-Mullen fail or lose face.

That contentious relationship meant that Davis-Mullen had little help in getting her project off the ground. Potential donors, wary of angering the mayor, were hesitant. The city contributed no money; even now it kicks in only $6,000 and some in-kind assistance such as Port-A-Potties.

Later on, as the company's popularity with critics and the public grew, there were ugly whispers that the troup would have an easier time if it got rid of Davis-Mullen.

In truth, if Davis-Mullen hadn't been involved, there would be no Shakespeare on the Common.

Davis-Mullen, citing the plays' diverse audiences, says she sees the performances as a way to bring high-caliber culture to all, particularly to working class residents who have in the past been put off theater by high prices or stereotypes about blue hair.

Her critics - and they are legion - figure that the company is simply a  political ploy, part of a master strategy to win Davis-Mullen higher political office.

That may be. Smart politicians like to associate themselves with good causes. It raises their profiles and is undoubtedly a good resume builder. But usually when they do that they join honorary committees, letting others do the work and showing up at the end to give a quick speech and claim all the credit.

Something more is at work here. There is a heart-felt intensity to Davis-Mullen's efforts with the company. It's something to which she has devoted enormous effort. It is quite obviously a cause in which she deeply believes.

Vision and persistence are the qualities Davis-Mullen has demonstrated in her efforts to bring theater to the people. They are not bad traits to have in any public servant.

In particular, as Davis-Mullen would doubtless argue, they are not bad traits to have in a mayor.

Tom Keane writes every Friday in the Boston Herald. He can be reached at tomkeane@tomkeane.com.