Seattle mayoral candidate Mike McGinn's softening of his anti-tunnel position may have backfired, according to The Washington Poll, a survey conducted by UW researchers.

Overall, the new poll shows Joe Mallahan with 44 percent support among likely voters, to McGinn's 36 percent. That's with 19 percent undecided and a 1 percent write-in vote.

The poll shows McGinn's support sliding since he announced last Monday he wouldn't necessarily block the tunnel that he'd spent the last eight months campaigning against. (His announcement came after a City Council vote on a tunnel agreement with the state.)

Before that, McGinn had 34 percent support, to Mallahan's 35 percent, according to the poll. A week later, Mallahan had surged to 45 percent support, while McGinn slipped to 29 percent.

Update: Note - the percentages in the above paragraph were for all registered voters, not just likely voters.

"It looks like it went very badly for him," said Matt Barreto, the associate UW political science professor who led the poll effort.

The poll sampled 400 likely registered voters in the city of Seattle, with a margin of error of 4.9 percent.

The McGinn campaign was quick to attack the poll this morning, questioning the sample size and even misspellings in the published poll findings. The poll release did misspell the names of Mayor Greg Nickels (as "Nichols") and County Executive candidate Susan Hutchison (as "Hutchinson").

"Pretty embarrassing that they couldn't even spell our mayor's name correctly in a poll attempting to be reputable," said Aaron Pickus, a volunteer spokesman for the McGinn campaign.

Barreto said those mistakes occurred because researchers were up until 2 a.m. finishing up their analysis (the poll was in the field from Oct. 14 until yesterday).

But he defended the methodology, saying the poll carefully sampled an appropriate number of voters in Seattle, despite the McGinn campaign's assertions.

The poll also used live interviewers as opposed to the computerized "robo calls" used by Survey USA, which conducts polls for KING-TV. (A Survey USA poll last week also found Mallahan ahead of McGinn.)

Essentially, Barreto said the UW conducted three polls -- contacting 726 likely voters to look at statewide initiatives, 400 voters for the King County Executive's race, and 400 in the city of Seattle to ask about the mayor's race.

In the King County Executive race, the UW poll shows County Councilman Dow Constantine pulling ahead of former TV newscaster Susan Hutchison.

Constantine had 47 percent of likely voters, to Hutchison's 34 percent. Not surprisingly, Constantine's greatest strength is in the city of Seattle, where he got 70 percent support.

The poll surveyed 400 voters countywide about the executive's race, with a margin of error of 4.9 percent.

(I wrote separately this morning about the poll's findings in two statewide ballot measures -- which showed Ref. 71 passing and Initiative 1033 going down.)