Antitax initiative-monger Tim Eyman has declared war on Sound Transit. While his latest offering, Initiative 1421, doesn't mention the words "Sound Transit," Eyman's intent is clear.

Eyman didn't return requests for comment for this story, but on the website for his organization, Voters Want More Choices, you'll find this: "Seattle-centric Sound Transit is going to try to impose $15-$25 billion in additional taxes this year—our initiative derails that," the site reads. "Bring Back Our $30 Car Tabs throws a much needed monkey wrench into what they're calling 'ST3.'"

The initiative would cap car-tab fees at $30 statewide. Today, those fees vary across the state and are higher in Seattle and the surrounding area because of an added fee that helps fund Sound Transit. In the proposal for the next expansion of light rail, Sound Transit 3, car-tab fees (known as the motor vehicle excise tax or MVET) become even more important. They would contribute $6.9 billion—or a quarter of the new taxes proposed for ST3.

"That's the equivalent of both the West Seattle and the Ballard lines," says Shefali Ranganathan, executive director of Transportation Choices Coalition, the advocacy group that will run the campaign for ST3. "That money would be wiped out."

Statewide, some smaller cities depend on the MVET for basic road projects. According to an anti-Eyman coalition of transportation, business, and labor groups and some city governments, slashing the MVET to $30 would blow a $3.4 billion hole in transportation funding over 10 years.

"The loss would be horrible," says Andrew Villeneuve, who founded the Northwest Progressive Institute and whose full-time job is basically opposing Eyman initiatives. "It would be awful. And people who do not use a car would be the worst affected."

To wage war on urban transit, Eyman will rely on mistrust of Seattle from voters elsewhere in the state. The only voters whose MVET fees fund Sound Transit are those in the Puget Sound cities and counties where Sound Transit builds projects. Yet, by railing against "Seattle-centric" Sound Transit, Eyman is building a campaign message urging voters all over the state to get back at a transit agency they don't even pay for. In a list of reasons voters should support the initiative, Eyman and his associates Mike and Jack Fagan slam Sound Transit and its "multi-billion dollar choo choo train boondoggles."

"If you want your $30 car tabs back, support our initiative," the site reads. "If you want to derail Seattle-centric Sound Transit, support our initiative." (A bit of irony here: Eyman is framing Sound Transit as too Seattle-focused in order to appeal to anti-Seattle sentiment in the rest of the state. Meanwhile, transit advocates inside Seattle are criticizing ST3 as too suburban. The plan would build more than four times as many miles of light rail tracks outside Seattle as inside the city.)

This isn't the first time Eyman has gone after car tabs or Sound Transit. In 1999, Eyman successfully pushed an initiative to replace the MVET with a $30 fee. The state supreme court ruled that unconstitutional, but the legislature cut the MVET anyway. Sound Transit's MVET dollars were grandfathered and the agency was allowed to continue collecting, but only recently got the authority to collect new MVET cash. They're hoping to put that new authority to use on ST3, the biggest ever light rail package to get a vote in the region. Eyman also attempted (but failed) to block plans to build light rail to the Eastside back in 2011.

Eyman will need to gather 246,000 valid signatures by July 8 to get this latest idea in front of voters. He has yet to launch a signature-gathering campaign, but looks ready to bankroll one. The I-1421 campaign has raised about $191,000, much of that rolled over from Eyman's antitax efforts last year. (Fremont landowner Suzie Burke, who has fought bike lanes and transportation taxes in Seattle in the past, has kicked in $5,000.) According to Public Disclosure Commission records, Eyman's group has $1.2 million in loans waiting to be directed to the car-tabs initiative—or another of Eyman's many ideas. Along with Eyman loaning himself $250,000, the supporters offering those loans have bankrolled his efforts before: Clyde Holland, CEO of a Vancouver, Washington–based real estate investment firm; Kenneth Fisher, CEO of Camas-based Fisher Investments; and Mark Needham, the owner of a Yakima "family fun center." Eyman often uses paid signature gatherers to make it onto the ballot. At $1 per signature, he'll need about $300,000 to fund that effort. The closer he gets to the deadline, the more he'll have to pay signature gatherers.

"Realistically, if he gets the money, he'll be on the ballot," Villeneuve says. "We're prepared to fight it."

If Eyman's initiative and ST3 both pass this fall, the Sound Transit Board would be left to decide which projects would be delayed or canceled, according to Sound Transit spokesperson Geoff Patrick. As thousands of new people are expected to move into the region, the choice won't be easy.

Eyman, who lives in Mukilteo, has made no secret of his dislike for transit that serves urban areas like Seattle and gets people out of cars and off highways. But as Sound Transit has rebuilt its reputation from near implosion in the 1990s, it's getting harder for Eyman to cast the agency as incompetent and wasteful.

"I think Eyman resents the fact that Sound Transit is delivering," Villeneuve says. "He wants the agency to be dead."