Among Gov. Kate Brown’s priorities this year is a legislative package that will provide badly needed funding for the state’s transportation system, everything from roads and bridges to mass transit and bike lanes. Many lawmakers agree with the general goal of House Bill 2017, the nearly 300-page transportation measure.

The bill may or may not be perfect, or even acceptable. That said, a threatened power play by the Service Employees International Union, the state’s largest public employee union, absolutely is not acceptable.

Union officials have made clear their willingness to sabotage HB 2017 if a business-tax package fails. The latter’s fate remains in doubt, in part because it will take a Republican in each house of the Legislature to get it approved.

The union’s threat brought a quick response from the governor. June 8 she noted the transportation bill is one of her priorities — and that it should be approved without regard to other measures. She doesn’t support the union’s tactics, she said, and she doesn’t approve of threats.

SEIU Local 503 is no doubt still stinging over the defeat last year of Measure 97, the gross receipts tax proposal. After all, the local donated $2 million to the cause, while its parent gave another $1 million. Still, 97 was defeated by voters in 34 of Oregon’s 36 counties.

But Brown is right. The state badly needs a transportation package, whether it’s the one in the Legislature or something else entirely.

What the state doesn’t need is SEIU or other public employee unions threatening to scotch legislation — any legislation — as a means to an unrelated legislative end, or any end, for that matter.

Union leaders should heed Brown’s words and back off. She seldom takes on public employee unions, which have been among her major contributors. Brown’s displeasure should send a strong message.