ST. PAUL  — Minnesota’s Legislature finalized a two-year spending plan just before a midnight deadline struck, but they adjourned with a near-certain special session looming to solve an education budget standoff with Gov. Mark Dayton.

In the final minutes Monday night of their five-month regular session, lawmakers rushed through remaining pieces of a nearly $42 billion budget in a flurry of rapid votes. But the governor has said he’ll veto the bill because it leaves out money for a preschool expansion initiative at the core of his agenda.

The next budget must be in place by July 1 to avoid a partial government shutdown, an almost unthinkable outcome given a nearly $1.9 billion projected surplus.

Legislators have worked around the clock the last few days to finalize provisions sweet and sour to the governor. The budget would boost funding to rural nursing homes but also increase health care premiums for more than 90,000 working poor residents on a subsidized health care program. Even the regulatory changes that Dayton dislikes are paired with additional funding for farmers affected by a deadly bird flu outbreak and a requirement for farmers to install buffer zones along waterways for cleaner water.

But no proposal drew more ire from Dayton than the Legislature’s $17 billion plan for public schools. Lawmakers from the House and Senate tried to craft a compromise to win over the governor, but those talks broke off with 30 minutes to go before Monday’s deadline.

After gaveling out 2015’s session, Republican House Speaker Kurt Daudt again urged the governor to reconsider his veto.

“The governor didn’t do his work to gain the support for his priority,” Daudt said. “I don’t know what difference a special session is going to make to change that.”

Democratic Senate Majority Leader Tom Bakk predicted it could take weeks to mend a rift over education and enable the Legislature to return for a brief special session. Dayton and top lawmakers would probably negotiate a new education deal before the full Legislature would be summoned.

“People need to go home and recharge and let some of the emotion out and come back,” he said.

The education budget might not be the only sticking point. Dayton has said little about his plans for other sections. Lawmakers guessed that if a special session was inevitable, other vetoes could follow.

State Auditor Rebecca Otto said Dayton should take down a state agency funding bill because of language that would give counties more room to contract with private companies for financial audits her office does. She said the measure would weaken oversight, even as supporters said it would reduce costs.

The governor’s plan to have the state foot the bill for half-day classes for all 4-year-olds got left out of the education bill that otherwise boosts payments to schools by $400 million. Bakk said he supports the preschool initiative but couldn’t get his GOP counterparts to pay for it. He said it’s up to Dayton to find a compromise with Daudt, whose Republican caucus has shown little interest in establishing a statewide program.

“I told him I’m not going to spend my whole summer in St. Paul,” Bakk said.

When and where they would hold a potential special session was unclear. Dayton has until the end of the week to decide on bills and could take weeks to make his mind up about when the full Legislature might reconvene. The House and Senate chambers will be off-limits beginning today because of a major Capitol renovation project. Dayton floated the idea of pitching a tent on the front lawn rather than renting space, a suggestion Bakk dismissed as unlikely. A downtown St. Paul hotel offered Monday to play host to a special session free of charge.

Meanwhile, another Dayton priority fell into place.

Lawmakers made late changes to a plan toughening rules for vegetation buffer zones separating farmland and public waterways in an effort to prevent chemical runoff. The revised plan calls for buffers of at least 30 feet in width but an average of 50 feet along public waters. The strips could be narrower along drainage ditches. Compliance deadlines would be late 2017 for public waters and 2018 for ditches. Farmers who don’t comply could face fines and orders for corrective action.

Rich Bischke of The Nature Conservancy in Minnesota called it “the most significant advancement in Minnesota water policy since 1991” and one that would improve water quality for wildlife.