Earlier today, the city council inched within an inch of approving the city’s share of the financing that will be use to construct a tunnel to replace the Alaskan Way Viaduct. Staunch tunnel opponent Mike McGinn, who’s running for mayor against fellow electoral neophyte Joe Mallahan, is not happy about this development.But maybe he should be.While it’s a bit unfair to say McGinn ran a one-issue primary campaign–that issue being the tunnel–it certainly was the dominant component of his platform, by a margin as wide as the Pacific Ocean. Such tunnel vision (ho-ha!) proved to be a brilliant strategy in a crowded primary field; McGinn bested incumbent Greg Nickels despite getting thoroughly dominated on the fund-raising front.Now that he’s made it to the general, McGinn has aggressively and admirably released plan after plan on topic after topic, some more grounded in reality than others. In spite of this, he’s still widely known as the anti-tunnel candidate. As a direct result, some would argue, he’s trailed Mallahan, who’s offered far less substance to date, in polls (Update: the P-I is reporting that the two are now deadlocked at 38 percent, with the rest undecided).Now let’s say the city council takes the tunnel issue off the table Monday, as expected. Mallahan will understandably proclaim victory, but I’m not sure how much credit he can realistically take, as the tunnel is undeniably Nickels’ baby (he’s thus far opting to simply thank the city council). Meanwhile, such an action might stand to benefit McGinn down the homestretch, as he can credibly say he fought the good fight while forcing voters to assess other aspects of his candidacy, and freeing up developer types to flock to his corner as he continues to tout urban density. Mike the Bike’s greenie/youngin’ base ain’t goin’ nowhere neither.