ST. PAUL — Minnesota lawmakers were putting the finishing touches on their wildly different plans for a $900 million budget surplus Thursday, pushing the spending debate away from public House and Senate floors and into closed negotiating rooms.

The Democrat-led Senate passed a mammoth budget bill that would devote the surplus to tax cuts, a new preschool program and measures meant to tackle racial disparities. Meanwhile, House Republicans were moving to approve a funding bill for state agencies that includes provisions slashing commissioner pay and imposing a hiring freeze across state government.

With those pieces in place, the real bargaining can begin behind closed doors, where legislative leaders and Gov. Mark Dayton will determine whether a compromise is in sight. The two-year, $42 billion budget passed in 2015 left nearly $1 billion unspent, giving lawmakers a second crack at tax cuts, transportation fixes and other unfinished spending priorities.

The final products from each chamber are worlds apart, leading some lawmakers to sound a note of caution.

“We are about to embark on the most challenging 3 weeks of this session,” Sen. Jim Abeler, R-Anoka, quipped from the Senate floor.

The Senate budget would draw down much of the surplus, while pursuing a stalled proposal to raise gasoline taxes for road and bridge repairs. The GOP-led House wants to save the leftover cash, splitting it between a transportation bill and tax cuts while drumming up some extra money through budget cuts to boost public school spending.

Looking at some of the provisions in the House’s budget, such as eliminating the state’s Film and TV Board, Dayton expressed exasperation: “I’m not going to revisit budgets that were passed last year. If that’s their position, I don’t know why we need to spend taxpayer money for the next three and a half weeks. Pack up and go home.”

Both parties agree that more money is needed for broadband Internet infrastructure, but the Senate’s budget put $85 million into the state fund, more than double what was passed in the House this week. Senate Democrats also included $25 million for a voluntary preschool program and funding for schools to hire more school counselors — both things absent from the House GOP budget.

But Republicans in the Senate took issue with the lack of funding for road and bridge repairs, trying to reroute more than $450 million of the surplus into dedicated transportation accounts. Democrats blocked it, arguing that would hardly make a dent in the billions of dollars needed over the next decade.

“It funds everything but transportation,” Sen. Scott Newman, R-Hutchinson, said. “There isn’t a penny in this bill, not a penny, spent on roads.”

The Senate budget passed 39-24 after nearly 8 hours of debate.

There’s still more to work out. House Republicans haven’t specified how much of the surplus they’ll earmark for taxes versus transportation. And while neither side has released their lists of public construction projects they hope to fund via borrowing this year, a scope has been set: Senate Democrats have promised to unveil a bonding bill that’s $1 billion or larger; House Republicans set the mark at about $600 million.

The House debate over a funding package for health care, state departments and public safety agencies veered into abortion as Republicans successfully tacked on amendments that would require licenses — and fees — at clinics that perform more than 10 abortions a year and would stop state-funded health care programs from paying for abortions. Democrats argued it would only hinder from getting a legal procedure. The full bill was expected to come to a final vote later Thursday evening.