Seattle's first major general-election season mayoral debate this afternoon was the first chance for the two candidates, Joe Mallahan and Mike McGinn, to engage each other on the issues. They did, exposing their two very different styles and challenging each other's primary-campaign talking points.

The debate at the Cinerama attracted about 375 people, organizers said. The Downtown Seattle Association, Greater Seattle Chamber of Commerce and other sponsors originally planned for just 150.

Mallahan acknowledged how little voters know about the two candidates, neither of whom has ever been elected, when he said, "We seem to have filled the house, perhaps more with questions than enthusiasm."

The two devoted much time to the Alaskan Way Viaduct replacement tunnel. McGinn opposes the tunnel and calls it the biggest tax increase in Seattle history, referring to the city's $930 million portion of the cost.

Mallahan says the decision on the tunnel has been made and the next mayor should focus on making sure the project is done on time and on budget.

For the first time, McGinn said there needs to be another public vote on the issue -- not so much, he said after the debate, on whether to replace the elevated highway with a tunnel, but on the taxes that would have to be raised to pay for a tunnel.

"We're probably going to have to vote on the viaduct anyway," he said during the debate. "This is Seattle."

On government efficiencies, Mallahan wants to reduce the use of outside consultants, saying they "distance leadership from accountability." McGinn said cutting consultants won't save money in the general fund, where the city is facing a revenue shortfall.

McGinn reiterated the portion of his campaign platform about Seattle Public Schools, which he says should show greater results or face a city-government takeover.

Voters in Seattle consistently support school levies, but the district still has inconsistent school quality and too high a dropout rate, he said.

Mallahan says the mayor has plenty to do without taking over the district. He thinks the city government should work with the district and use the funding in the Families and Education Levy to pay for changes.