Early in Minnesota's 2008 legislative session, backers of a planned light-rail connection between Minneapolis and St. Paul are expected to propose the biggest single transportation bonding request in state history - a $140 million down payment on the nearly billion-dollar project.

But if legislators are consumed by debates over crumbling bridges after the Interstate 35W bridge collapse, Central Corridor supporters may be in a tricky spot - asking for Minnesota's biggest single transportation check ever without looking like they're taking money away from fixing the state's aging infrastructure.

That could rekindle a long-standing debate about a half-cent metrowide sales tax to help fund mass transit projects, with one major difference from years past: There are signs of gathering support.

"You tell me," said Richard Krueger, executive director of the Minnesota Transportation Alliance. "How does something like the Central Corridor get done without a metro sales tax?"

In cities such as Denver, San Diego and Salt Lake City, local sales taxes are being used to pay for transportation systems, including new light-rail lines. And although the Twin Cities tax could raise more than $220 million annually and make the funding puzzle for the Central Corridor easier to solve, it has faced opposition from Gov. Tim Pawlenty, businesses and others.

While past effort to pass a sales tax failed, supporters now see hope. For the first time, the influential League of Minnesota Cities supports some form of a sales tax to pay for transportation, and there are signs that the business community is reconsidering its position.