SALEM — Oregon Democrats’ multibillion-dollar business tax and education funding plan is on its way to Gov. Kate Brown’s desk, after the state Senate passed it on a party line vote Monday afternoon.

The vote on Democrats’ top priority this session came just hours after Republicans returned from a nearly weeklong boycott to protest the bill’s fast-track passage through the Legislature.

With three-fifths supermajorities in both chambers, Democrats can pass tax increases without a single Republican vote. Denying the 20-member quorum necessary to hold a Senate vote on the bill was one of the tools Republicans had left, and it proved insufficient for them to achieve any immediate changes to the plan.

Passage of the bill clears the way for Democrats to move on to other priorities, including a bill to cap greenhouse gas emissions and dozens of state budget bills that lawmakers must pass by the end-of-session deadline at the end of June. House Bill 3427 passed 18-11, with Republican Sen. Jackie Winters of Salem excused.

In speeches on the Senate floor, Democrats described the education legislation as a historic investment in education that has been necessary ever since voters restricted property taxes through ballot initiatives in the 1990s.

Sen. Lew Frederick, a Portland Democrat, said House Bill 3427 “is a long overdue change and a historic moment.”

Sen. Rob Wagner, a Democrat from Lake Oswego, said he “heard from constituents in my district that this is a once-in-a­-generation vote.”

Sen. Arnie Roblan, a Coos Bay Democrat who was one of the bill’s architects, spared no detail as he reminisced about the last year of work on the plan as lawmakers traveled to visit schools around the state and set to work in multiple committees.

“We started this journey 16 months ago,” Roblan said, referring to when Senate President Peter Courtney formed a committee to begin researching unmet education needs. “And today is the end of that journey.”

In a briefing with reporters after the vote, Roblan, Senate Democratic Leader Ginny Burdick of Portland and Sen. Mark Hass, D-Beaverton, each described passing the bill as the highlight of their individual political careers.

Education and early childhood advocates and unions that represent teachers and other public employees cheered the bill’s passage, describing it as “historic,” a “turning point for education in Oregon” and a “new day for education.”

The vote was possible only after senators returned to the Capitol Monday as part of a deal with Democrats that they would kill proposals to tighten Oregon’s vaccine mandate and gun regulations.

Courtney credited the governor with playing an important role in negotiations with Republicans. “Without her, we wouldn’t be here today,” Courtney said, although he declined to go into specifics.

In floor speeches before the vote, multiple Republicans agreed with Democrats that the state needs to boost spending on schools and other education programs.

But they said the gross receipts tax in House Bill 3427 is the wrong way to raise that money and warned that the rising costs of Oregon’s underfunded public pension system will quickly cut into the new revenue.

“The one thing I haven’t heard today is the 1,000-pound monster that I hear from all my school boards and that is the PERS problem,” said Sen. Herman Baertschiger Jr., the Senate Republican leader from Grants Pass.

Sen. Betsy Johnson, a moderate Democrat from Scappoose who sometimes votes with Republicans, said she decided to vote for the plan based on her trust in Democratic leaders' promises that they would get substantive changes to the pension system passed this session.

Courtney told reporters after the vote Monday that he is worried about his ability to line up votes from within his own party for pension changes. Senate Republicans had offered last week to provide five votes in support of a pension “fix,” suggesting Democrats in the chamber could not pass it on their own.

The threat that opponents might refer House Bill 3427 to voters has been hanging over the bill all session, but it’s not clear that interests that want to overturn the bill would be able to muster the financial and organizational support to mount a successful campaign.

Democrats went into the session with support for a tax increase from Oregon’s largest company, Nike, and have since picked off other potential opponents in the business community by negotiating limited concessions on the bill. At the end of April, Oregon Business & Industry — the state’s largest business association — announced it would not support a referral campaign.

Opponents cannot begin the process of referring the plan to voters until the governor signs it into law, which she is expected to do within the five-day deadline.

The plan would impose more than $1 billion a year of taxes on an estimated 40,000 businesses’ gross receipts over $1 million. The first $1 million in sales would be exempt from the 0.57 percent tax, and businesses could subtract 35 percent of either their labor or capital costs from their total sales.

In recognition that businesses will pass some of the cost of the tax along to consumers, the plan includes a 0.25 percentage point personal income tax cut for all but the highest income earners.

Starting in 2020, roughly half the money would go to for grants to local districts and 20 percent to programs serving toddlers and preschoolers. The remainder would be split between full funding for a 2016 voter-approved measure to expand career-technical offerings and anti-dropout programs and initiatives to improve schools’ performance statewide.

Roblan said local school officials wanted to make sure the funding formulas would not be overly prescriptive.

“Districts said, ‘We need more money and we don’t want you to tell us how to spend every penny,’” Roblan said.

Sen. Cliff Bentz, a Republican from Ontario, said he personally observed the need for more classroom funding while serving on local school boards.

But when it came time to develop the tax provisions in the legislation, Bentz said he was excluded from the “meaningful” private meetings where Democrats made key decisions.

“I got to attend the public (meetings),” Bentz said. “It was discouraging to be at the table and to be ignored.”

— Hillary Borrud | hborrud@oregonian.com | 503-294-4034 | @hborrud

Visit subscription.oregonlive.com/newsletters to get Oregonian/OregonLive journalism delivered to your email inbox.