OLYMPIA — Sound Transit leaders have set out on another journey to raise billions of dollars from taxpayers so they can bring light rail to Everett, Tacoma and Redmond.

If all goes as planned, it will make the ballot in November 2016 and ask voters to approve a hike of the property or sales tax or car-license fee to generate up to $15 billion for system expansion.

But first, Sound Transit must obtain the authority from the Legislature to raise these or other taxes. Last week the board of directors, a collection of elected officials from Snohomish, King and Pierce counties, voted unanimously to start talking with lawmakers in hopes of securing support during the 2015 session.

There’s no guarantee. Lawmakers also are eyeing the pocketbooks of taxpayers to fund a statewide transportation package.

“It is a heavy lift. There’s no question about it. It may not happen,” said Everett City Councilman Paul Roberts, the Sound Transit board’s vice chairman. He, Edmonds Mayor Dave Earling and County Executive John Lovick represent Snohomish County on the board.

Sound Transit’s plans shouldn’t be viewed in competition with any state package, he said. Both are needed to maintain and improve a transportation system that in Puget Sound is increasingly defined by bottlenecks and gridlock, he said.

“We understand the challenges facing the Legislature,” he said. “But if you want to have a viable, thriving economy, then you can’t choke it to death by not having the infrastructure necessary for that viability.”

Sound Transit last went to the ballot in 2008 with a measure that increased the sales tax by a half-cent within district boundaries, which include Everett, Edmonds, Mukilteo and Lynnwood. Communities north of Everett and east of I-5 are outside the boundaries.

That measure, known as “Sound Transit 2” and dubbed ST2, is paying to extend light rail from Northgate Mall in Seattle to Lynnwood by 2023. Voters passed Sound Transit 1 in 1996.

Next month, Sound Transit leaders are expected to approve a new plan prioritizing new projects in all three counties over a 15-year period. The desired ballot measure, which is being referred to as ST3, would generate between $9 billion and $15 billion.

Extending light rail from Lynnwood to Everett sometime in the 2030s is certain to be on the list.

A 2013 Sound Transit analysis found that a Lynnwood-to-Everett line passing by Paine Field would stretch for 15.7 miles and cost up to $3.4 billion to build. A direct Lynnwood-to-Everett connection along I-5 would cover 12.6 miles and cost up to $2.2 billion.

Roberts said he’s drafted an amendment to the plan to ensure the line travels through the southwest industrial area, where Paine Field is located, so workers at Boeing and surrounding aerospace firms can access it.

As a part of the process, Sound Transit also must decide what taxes it wants to raise before the Legislature will consider granting it the authority to act.

Board members, at their Nov. 20 meeting, voiced support for delivering a bill to lawmakers containing several taxing options.

One would be a boost in the property tax assessment of up to 25 cents for each $1,000 of assessed valuation, which works out to roughly $75 annually for a $300,000 house, according to a Sound Transit press release.

Another possibility is bumping up the sales tax by a half-cent. Or the board could look to the car-tab fees and increase the motor vehicle excise tax rate from 0.3 percent to as much as 0.8 percent.

Roberts said no decisions have been made — he is looking for other potential streams of revenue, too.

“This is a starting point for discussion,” he said. “There’s a lot of discussion ahead on this.”

Jerry Cornfield: 360-352-8623; jcornfield@heraldnet.com.