Murray could win by coming across as a reasonable, statesmanlike guy with long experience as a legislator (11 years in the house followed by five years in the senate), in contrast to inexperienced McGinn, who had never served in public office before being elected in 2009. But let's say Murray doesn't run---or that both McGinn and Burgess make it through the primary (far from certain, but go with me here).
How can Burgess beat the mayor? Contrary to current conventional wisdom, it won't be because he supported the deep-bore tunnel, McGinn's premier (and, really, only major) issue for his first two years in office. Instead, Burgess, a former cop, can win by focusing his campaign on what he knows best: Public safety. (Fizz, in this case Josh, made the case against Burgess yesterday).
Here's why I think a public-safety campaign can defeat McGinn in 2013. First, the Seattle economy isn't improving as fast as the city initially predicted. That means more years of austerity, more years of budget cuts, more years of reducing spending in every department, including police. It's the same problem that plagues Obama: When you don't have money to spend (and when you can't raise revenues---no one is suggesting a public-safety levy), departments tend to deteriorate.
So far, SPD and SFD have been largely spared the brunt of city cuts (which have fallen most heavily on the Department of Planning and Development and the Seattle Department of Transportation---ironic, given that McGinn gets blasted for spending too much on bikes), but they haven't been entirely spared. In future years, the city is going to have to make further cuts to police and fire. That's bad for the mayor, who gets blamed when things are bad (and takes credit when things are going well). The prolonged recession also means there's more need for social services, but less money: A perfect storm for "nuisance crimes" like public inebriation and aggressive panhandling.
So cuts will happen, the neighborhood policing plan---which was supposed to include 30 new cops every year but has been on hold since it was first adopted in 2007---won't get implemented, and McGinn will take a big political hit.
A couple of things could exacerbate the political fallout for McGinn. The first is a high-profile murder, like the death of 20-year-old Christopher Kime during the catastrophic Mardi Gras riots in 2001. That public safety disaster (combined, of course, with smashed windows at WTO), doomed then-Mayor Paul Schell's chances for reelection (like Greg Nickels in 2009, he didn't even make it through the primary).
The second is that street disorder (everything from shootings to aggressive panhandling to obnoxious drunks) in places like downtown fails to improve or gets worse. Whether you agree or not, the perception is that places like Third and Pine (where a man was stabbed as recently as August 22) and Belltown (where windows were literally broken earlier this summer, giving new meaning to the "broken windows theory") are less safe than they used to be.
For Burgess, promising to hire more cops and put them in trouble spots is both credible and a surefire win. Credible because he's an ex-cop and chair of the council's public safety committee; a surefire win because McGinn won't have the money to put more cops on the street---all he can do (and has done) is shift officers around, moving cops between precincts and transitioning beat officers from cars to the streets.
There's are two unrelated problems that will make it hard for McGinn to stake his claim as the public safety guy: First, he doesn't have a major win under his belt. So far, anyway, he's rolled out a lot of initiatives, but they're either uncontroversial (the Families and Education Levy, which typically wins with about two-thirds of the vote) or unfunded (the Jobs Initiative, which mostly involves minor tweaks to regulations).
Second, his reputation is the polar opposite of a public safety guy; he's got a rep for being a hippie. McGinn, fairly or not, is known as the bike guy. Yes, SDOT only spends about 3 percent of its budget on bike facilities. No, it doesn't matter. McGinn ran as an environmentalist, and the public imagination simply isn't broad enough to comprehend an environmentalist who's also tough on crime. An ex-cop who's tough on crime, on the other hand? That's an easy sell.