If Seattle residents make Mike McGinn the city’s next mayor, he will give them a chance to vote on a light-rail line connecting Ballard and West Seattle, he said at a press conference today. McGinn would place the measure on the ballot within two years of taking office—most likely meaning the November 2011 election—asking for hundreds of millions of dollars.

“If city voters support the plan, and agree to raise their taxes to fund it, we will get it built as quickly and efficiently as possible,” McGinn wrote in a statement. “Neighborhoods like Ballard, Belltown, Fremont, Queen Anne, and West Seattle are geographically too far to be served [by] the Central Link light rail line,” he said. “We owe it to the residents of these neighborhoods to provide them with real high-capacity transit choices.”

McGinn’s proposal is somewhat unusual, in that he pledges not to create a new city-run agency, instead relying on the regional Sound Transit and King County Metro, both which serve areas larger than on city. However, there is precedent. The First Hill streetcar line, approved last fall by voters in the Sound Transit 2 package, will be paid for exclusively with Seattle tax money, but Sound Transit conducted “a lot of the initial planning studies for it and where it would go,” says Sound Transit spokesman Bruce Gray.

Sound Transit is studying several light-rail extensions. However, the slated date for voters to approve those plans is 2016, Gray says. And McGinn argues that, without an expedited vote, it could take 20 to 30 years before light rail reaches Seattle's western neighborhoods.

McGinn proposes frugal construction by “heavily leveraging existing city right of way to create transit only lanes and corridors.” He notes that Portland just opened its fifth light-rail line, requiring only three years of construction and $575 million.