A new poll of 600 likely Seattle voters shows Mayor Greg Nickels poised to make it through the Aug. 18 primary, but it's not clear who will face him in November.

The Washington Poll, conducted by researchers at the University of Washington, shows Nickels leading with 23 percent of the vote.

T-Mobile executive Joe Mallahan was next, with 11 percent, followed by former Sonic James Donaldson, with 10 percent.

Seattle City Councilmember Jan Drago and environmental leader Mike McGinn both came in at 9 percent.

The poll had a margin of error of +/- 4 percent, so any of those candidates could advance past the primary.

"There is a strong four-way race for second place, and any one of the four challengers could make the runoff. It depends entirely on candidates' ability to mobilize supporters," said Matt Barreto, a UW assistant professor of political science who led the researchers, in a press release.

More than a third of those polled said they are undecided.

When asked to name top city issues, voters listed the Alaskan Way Viaduct -- possible good news for McGinn, who is the only major challenger to oppose the $4.2 billion tunnel project.

The poll also found strong opposition to Seattle's 20-cent fee on plastic and paper grocery bags, with 55 percent opposed and 41 percent in favor of the fee.

I'll have a little more on the mayor's race numbers in a bit.