SENATE PRESIDENT Tom Birmingham’s campaign for governor is like the shirt worn by the Riddler on the old Batman television show: one giant question mark. The central question about Birmingham’s campaign is how the former Rhodes scholar manages to keep driving himself through the drudgery of individual-contact, retail campaigning despite being so far behind the front-runner, Treasurer Shannon O’Brien, in all the polls, including his own. (He and his handlers trumpet a July poll showing Birmingham 11 points behind O’Brien. But an internal O’Brien poll reportedly shows the treasurer with the support of 35 percent of respondents, former secretary of labor Robert Reich with 25 percent, and former Watertown state senator Warren Tolman tied with — if not ahead of — Birmingham at around 12 percent.)

Although his fortunes are waning and his new round of television ads has yet to catch on, Birmingham has set a breakneck pace on the campaign trail. Since the conclusion of the Senate session in July, he has filled his day planner with events aimed at winning voters. Last Wednesday, August 14, for instance, he raced from the site of Dorchester’s Edward Everett School, where he received the joint endorsement of the Mass Teachers Association (MTA) and Mass Teachers Federation (MTF) — the first time both groups have ever endorsed the same candidate in a primary — to Roxbury’s Madison Park High School. Following that, Birmingham lobbied community leaders in Roxbury and later showed up to glad-hand potential voters in Norwood.

There can’t be any question that this state of affairs represents a comedown from the time when Birmingham first tossed his hat into the gubernatorial ring back in 2000. While it’s true that he still boasts well-funded campaign coffers, endless tenacity, and a bevy of institutional endorsements — including a nod from the powerful AFL-CIO — it’s important to note the extent to which the Senate president’s campaign team has dialed down its expectations. Back in 1999 and 2000 — when Birmingham was assembling his campaign war chest, and the most likely prospective Republican opponent was a weakened Paul Cellucci or, later on, a listless Jane Swift — many political insiders saw him as the candidate to beat. Two of the savviest campaign operatives in Massachusetts politics — Jack Corrigan and Michael Shea, both veterans of Michael Dukakis’s gubernatorial and presidential efforts — got behind his campaign. The expectations peaked in January 2002, when Birmingham’s advisers put out the word that the Senate president might try to win the state Democratic Convention outright, by garnering such a high turnout at the local Democratic caucuses (during which convention delegates are selected) as to guarantee him a vote of more than 50 percent on the convention’s first ballot.

Nobody talks about any of that now. These days, you hear about how Birmingham, even as Senate president, represents only one-fortieth of the state, a line that even popped up in a Boston Globe profile of the candidate this past Sunday. You also hear his allies talking about how O’Brien is now making her third run at statewide office; about the national celebrity of former secretary of labor Robert Reich; and about how even former Watertown state senator Warren Tolman — whose candidacy, until only recently, had been treated as an incredible long shot by the press — has experience with statewide campaigning, having run for lieutenant governor in 1998.

The interesting thing about this turnabout is how little you hear about it in the press. Indeed, the story about Birmingham and the 2002 campaign for governor is that he’s not the story. The front-runner, for now, is O’Brien, who has the support of more than 30 percent of voters in everybody’s polls. And Reich is battling the publicly financed Tolman for the insurgent’s mantle.

Despite the media’s seeming indifference to Birmingham, however, he is at the center of what may be one of most interesting stories of the campaign. A man who has been at the center of Beacon Hill action for six years is now entering the most important month of his political life. If he wins the primary, he will have engineered one of the greatest upsets in Massachusetts politics. If he loses, his political career will almost certainly be over, as he is stepping down from his state-Senate seat. How he goes about these next four weeks will go a long way toward showing what kind of politician — and what kind of man — Birmingham is.

"I’m not discouraged ... when we get our message out, we move forward very strongly," the candidate says. "I think we’ve got the biggest upside of all. I’m not discouraged at all. In fact, I’m encouraged."

A graduate of Harvard Law School, Birmingham states his case so emphatically that only two conclusions can be drawn: either his people know something about the statewide electorate that nobody else knows — or he’s so myopic that he just doesn’t see the other factors in the race.

BIRMINGHAM’S REPUTATION with reporters, voters, and fellow politicians is no secret: he’s sometimes shy and sometimes aloof. When, for example, many of our local leaders basked in the delight of political nirvana — a trip to the 2000 Democratic National Convention in Los Angeles — Birmingham, by contrast, seemed pained and uncomfortable. As the likes of Tolman patrolled the pool at the Beverly Hills Hilton, shaking hands and patting activists on the back with panache, Birmingham stood in the hotel’s lobby, somewhat sullenly smoking a cigarette (he still smoked back then). For most of the convention’s attendees, it was a glimpse of the political big time; for others, it was a chance to unwind — away from lurking constituents ready to launch a harangue (an ever-present danger for the local city councilor, state representative, or state senator). But for Birmingham, it all seemed a chore. He took the opportunity during his LA visit to meet with friends from his Harvard and Oxford days.

But that reticent Birmingham is gone — along with the cigarettes he gave up last year. On the trail, he’s quick to make a joke and call a reporter a wise guy. The new Birmingham showed up at Norwood Common at 7:15 p.m. on the night of Wednesday, August 14, undaunted by the record-setting temperature of 101 degrees. The Wild Rovers, an Irish-music group, led a largely elderly crowd of roughly 200 in the singing of "McNamara’s Band." Temperatures remained steamy, well into the 90s. Birmingham, dressed in a crisp blue suit with a red tie, strode jauntily onto the common carrying an ornate shillelagh festooned with the logo of the plumbers union, local number 12. A young volunteer and member of the union, Jamie Beaker of Norwood, had crafted the Irish walking stick out of sugar maple. The gift appeared to infuse the smiling and jovial Birmingham with energy.

Norwood selectwoman Helen Donohue, who last year helped State Senator Stephen Lynch — another urban labor favorite — in his run to replace Congressman Joe Moakley, welcomed Birmingham and took him deep into the common to begin greeting voters. "You’ve got the best seat in the House," the Senate president remarked to a man sporting a mustache and mullet, who was seated on a lounge chair. He shook another hand, and this time the voter mentioned Birmingham’s mother, Agnes, who has become popular on the campaign trail. The candidate spotted a man holding a purple SEIU baseball cap and asked, "Is that SEIU? They endorsed me the night before last." Another hand. This man told Birmingham, "I used to play basketball with your brother Jimmy at UMass." Birmingham replied: "I’ll tell him."

It was a brisk, methodical pace. Up and down the rows of people walked Birmingham and Donohue, clad in kelly green. "Jackie, Jackie," cried Donohue to one voter. "This is Tom Birmingham. He’s a good man. He’s running for governor." Then, near the end, Birmingham met someone who momentarily jarred him out of his routine: Walter Ryan, a former veterans-services agent. "You don’t have to worry about my vote," said the white-haired old-timer. "I used to work with Jackie. I used to work with Jackie, your father." First Birmingham was surprised. Then he broke into a wholly natural gin. "He’s the spitting image of his father," Ryan added.

When Birmingham finished, he took a moment to rest. His crisp white shirt was soaked through with sweat. He was happy — in a way he never appeared to be while in budget negotiations with House Speaker Tom Finneran. "It was a good hit, as they say," he said. "There’s no substitute for talking to people personally and having a moment of direct contact." Asked about his hands-on style — so different from his behavior on Beacon Hill — Birmingham says, "In the building, I try to keep people at arms' length to preserve my independence from the [Senate] body, but that’s not the way to campaign."