The rule in Portland mayoral races is that to be elected mayor, you have to win an outright majority, in one election or another. It can happen, and has happened, in primary elections – it did four years ago, when San Adams won outright in May. But it is not likely to happen this year: The probability is that two candidates will go on to campaign until November, when one of them will get the job.

While everyone could be surprised in another week, more likely the effective three-way race between business executive Eileen Brady, state legislator and activist Jefferson Smith and former council member Charlie Hales, simply will be reduced to a two-candidate struggle into the fall. The polling in recent days – a batch of them have been released, from the Oregonian and KATU and others – showing a variety of different responses. (Hales, for example, leads in one poll and is in third place in another.) Generally, the three are at least in shooting distance of each other, and in some polling within the margin of error of each other. (Complicating this: There’s not much philosophical difference between them; this is a competition between style, emphasis and experience.) But this much is consistent: All three are getting substantial portions of the vote, enough that the idea of any one getting to 50% seems highly unlikely. Factor in the 20 other minor candidates for mayor, who have no realistic chance of winning but will siphon away some percentage of the vote (maybe 10 or 15 percent), and the idea of a runoff becomes a near-lock.

The real question, most likely, is: Whose musical chair will be taken away?

It’s almost impossible to be sure. Our uneasy guess is that it will be Hales. He like the others has substantial support, including strong business support (and an Oregonian endorsement). His time on the city council gave him some base. But he seems to have had little momentum or emotional push, and he’s had more bum headlines than the other two. Contrast him with Smith, who started in early polling as a clear third-place candidate, but has picked up steam steadily since. He shows a first-place finish probably less often than the others, but he has significant growth. And his long-time activist background has give him a terrific campaigning base.

So Smith seems somewhat likely to make the runoff, and so it seems with Brady, a co-founder and long-time executive of New Seasons Market – she too seems to have a highly energized support base. She comes at the office, at this point, as a little more of an outsider than the other two (not that you can press to point too far), and in recent decades Portland has had some affection for outsiders (or perceived outsiders) running for the office. And one polling result seemed to show Brady ahead among voters who already have cast their ballots.

So the best guess here is a Brady and Smith runoff. But this is a close race, and quirks the race can yet skew the outcome.