Is new Seattle Mayor Mike McGinn really intent on blocking the deep-bore central waterfront tunnel, or just trying to watch out for the city's fiscal future? Seattle politics is twisted into a pretzel about this question, and the mayor is mostly evasive when people try to press him. Asked directly, he tends to change the subject to the crumbling seawall, much as a have-it-both-ways politician will reframe the abortion question to a call for more adoptions.

I put this critical question earlier this week to the mayor's communications director, Mark Matassa, a very trustworthy figure, and I think I detected a shift in the message. "As long as the city is not paying for cost overruns, McGinn would not stand in the way of the project," Matassa said. Asked if the mayor would be throwing up other roadblocks, aside from the cost-overrun question, Matassa said no, adding, "I think that he would never be an enthusiastic backer of the tunnel, but that, as he has said, he would not stand in the way of the project as long as it were determined that Seattle would not pay for cost overruns."

Few believe the mayor's position has been (or still is) that simple. Former Mayor Charles Royer, a strong tunnel backer, told a group of waterfront planners last week that he thinks we have a serious problem with the city council favoring the tunnel (6-3 or 7-2), and the mayor all-but-explicitly against it. A key city councilman, Tim Burgess, claiming to have gotten a straight answer out of McGinn, says flatly: "He wants to stop the tunnel."

These people and other tunnel advocates credit McGinn with an artful strategy of raising concerns, especially about the cost-overruns — referring to a provision the legislature slipped in at the last minute, saying taxpayers of Seattle are on the hook for the cost of the tunnel beyond the state's committed share. Raise enough dust and objection and eventually the proponents splinter and give up or enough time passes through delaying tactics that the cost escalates through inflation to where the state pulls the plug.

Not so, insists Matassa. There's just the one issue, and the mayor deserves credit for his lonely stance in seeing that the city doesn't wander down that murky path and end up with a huge bill of Big Dig dimensions. This past week, for instance, the mayor could have asked the Port of Seattle to delay on its memorandum of agreement to spend $300 million as its share, a critical step in getting the state able to request proposals from the contractors to build the huge project. It's indicative of the anxious speculation about what McGinn's up to that the Port was privately very worried about such a mayoral surprise. It's evidence of McGinn's new and more limited position (only the cost overruns matter) that there was no such request. (Many more opportunities for delay lie ahead.)

So why don't the tunnel advocates take the mayor at his word (or call his bluff) and work with him to remove the cost-overruns provision? Simple reason: trying to do so risks collapsing the whole political house of cards erected to get the tunnel plan passed. Some teetering House Democrats could only be induced to vote such a pro-Seattle measure if the stick-it-to-Seattle provision was put in, even if it's of dubious legality. (States build state highways, and can't conjure up mysterious local entities to pay if they screw up. And how many other localities are going to like that legal precedent?)

So the decision of tunnel advocates, from Gov. Chris Gregoire on down, was not to stir up this sleeping dog, especially in this tax-and-spending-stressed session. Doing so would give tunnel opponents like House Speaker Frank Chopp a chance to undo the vote, send the money elsewhere, and cram a new Viaduct down Seattle's throat. Better to build now, while contractors will bid low, avoid cost overruns, and take your chances in the courts if the zany provision ever has to be tested.

That McGinn won't go along with this don't-ask strategy leads to several lines of speculation. Among them: He's not a team player. He's still on the campaign trail scoring sound-bite points by playing to fiscal conservatives about the cost and pro-transit greens about an auto-oriented tunnel. He's a three-cushion-shot pool player who's devised a clever, I-never-said-I-was-against-the-tunnel strategy for blowing the tunnel up. He knows the tunnel coalition is winning, and he just wants to signal to the greens that he's really with them, and so can't openly work for the tunnel.

The puzzling over the mayor's real motives goes way back. He won the primary by flatly opposing the tunnel, then switched late in the general election to saying, since the City Council had just endorsed the idea 9-0, that it was a settled issue and he wouldn't block the tunnel even if he didn't like the idea. Shortly after being elected, he was giving have-it-both-ways interviews, stressing his "personal" opposition to the tunnel. He let some political leaders believe that he was passing beyond this issue and leaving it to others to push the idea through.

It's odd. The textbook way of dealing with this is along the lines of: "Look, I never thought the tunnel was a good idea, since it's risky and too auto-centric. But the city and the state have finally reached an agreement on this, and I certainly don't want to risk getting a new Viaduct or more years of the unsafe Viaduct. So, I'm going to work very hard to make the new plan happen, and to protect the city's fisc. And I'm going to stick to my principles about fewer highway lanes and more transit in all sorts of other opportunities we will have, starting with 520." And then he'd have to prove he means this by staying on the script and not dashing off with a new, out-of-phase plan for the seawall. Nor would he join forces with Frank Chopp, still seething in a kind of royal rage that his plan for a new viaduct was scuttled by the legislature, and who would love to get that issue about cost-over-runs before his caucus so they could see the folly of their Seattle-helping ways.

Instead, we have McGinn's byzantine path on the issue. The danger to his mayoralty is that it erodes trust, makes him look devious and "political," while he talks about reform and openness and ending the Nickels era of back-room deals with powerful interests. He might prevail on this issue, cementing his support from the deep greens, but at a possibly fatal cost to his credibility and effectiveness on other issues.

Lastly, could he actually prevail? While historians may some day exonerate him for warning about costs that got out of hand, in the short term (meaning his first mayoral term), it's hard to imagine that he can turn the juggernaut for the tunnel. Gov. Gregoire, while slow in coming to this solution, is now very determined to push it through, especially in this climate with so many commuter-and-transportation-dependent jobs in the balance. The state has the power to brush aside a city's foot-dragging and obstructionism on a major highway project, and few doubt that Gregoire, once she has the bit in her mouth (as she does), will back off. She can be a very determined leader, once riled up.

My hunch is that the pragmatists are gaining more sway in Team McGinn, as with Team Obama, and that he is already starting to back away — on the seawall, on other opportunities to stall, and by narrowing his war against the tunnel to a single front, the cost-overrun clause, where there is little likelihood of it actually coming up for a new vote. He needs to find some issues where he can lead and win, not just be a sniper.