AUGUSTA, Maine — By late Tuesday night, the Legislature had taken the first steps toward approving a two-year, $6.7 billion spending plan and averting a government shutdown.

Representatives in the House gave the compromise unanimous support in an initial vote Tuesday evening, and the Senate unanimously passed a slightly modified version several hours later around 10:30 p.m.

The deal, an amendment to the spending bill crafted by a majority of the budget-writing Appropriations Committee earlier this month, was crafted by the four party leaders in the House and Senate, and includes tax and welfare reform provisions that had been sticking points in negotiations for months. Lawmakers were briefed on the plan Monday night, but details were tightly sealed from the public until just a few hours before the budget hit the House floor.

The Legislature was expected to continue meeting late into the night as the House and Senate took further votes and hashed out disagreements over amendments.

Barring any sudden and unexpected snags, leaders in both chambers expected the bill to pass final enactment and be sent to Gov. Paul LePage before lawmakers left the State House late Tuesday night or early Wednesday morning.

LePage has said he will veto the bill, but with two-thirds support needed to pass the budget in the first place — the same threshold needed to override a veto — the governor is not likely to be a factor.

The compromise bill includes an estimated $71 million overall tax reduction for Maine residents, while an additional $80 million is invested in K-12 education. It also includes increased property tax relief and additional funding for nursing homes and community medical services that continue to have long waiting lists.

“There is something here for everybody,” House Majority Leader Jeff McCabe, D-Skowhegan, said during a floor speech. “Everyone has had to be flexible. It’s a true compromise and an example of how divided government can work.”

The accord is a culmination of turbulent tax negotiations that at some times seemed destined for failure. LePage, Democrats and Republicans each proposed plans, but none was able to win the support of a supermajority of lawmakers needed to pass a budget bill.

That left legislative leadership — House Speaker Mark Eves, D-North Berwick; Senate President Michael Thibodeau, R-Winterport; House Minority Leader Ken Fredette, R-Newport; and Senate Minority Leader Justin Alfond, D-Portland — to work through the sticking points that remained. The stakes are high: If a budget isn’t passed by the end of the month, government would shut down.

Compromise was elusive. House Republicans threatened to torpedo an earlier deal struck by their Senate colleagues and the Democrats. That agreement included neither tax cuts nor welfare reform, both of which the House GOP demanded be a part of any agreement.

And so they are.

All told, about 580,000 Maine families would see an overall tax decrease, according to a Maine Revenue Services analysis of the deal. About 117,000 Maine families would see an overall tax hike.

Under the compromise budget amendment, Mainers at all earning levels would receive an income tax cut. Income up to $21,400 would be taxed at 5.8 percent, income between $21,400 and $50,000 would be taxed at 6.75 percent, and income above $50,000 would be taxed at 7.15 percent.

The tax reform plan also includes changes in deductions and credits designed to target income tax relief to low- and middle-income residents, including a near doubling of the standard deduction, which would be pegged to inflation into the future. It also expands the Earned Income Tax Credit, which would be made completely refundable. Other deductions are phased out for higher earners.

Income tax cuts were a demand of Republican budget negotiators while Democrats said any cuts must be tailored to benefit Maine’s middle class. According to a distributional analysis created by Maine Revenue Services, about 75 percent of the income tax cut would be distributed among the bottom 90 percent of Maine’s earners.

The income tax cuts are paid for in part by increases in the sales tax.

Under the deal, the sales tax would rise to 5.5 percent from a scheduled rate of 5 percent. The tax on restaurant meals and other prepared foods would rise to 8 percent from a scheduled 7 percent rate, and the tax on motels and hotels would rise to 9 percent from a rate of 7 percent.

The deal also includes a new Sales Tax Fairness Credit for low-income Mainers to offset the regressive nature of sales tax increases. All single filers would receive a $125 credit, and all joint filers would receive a $250 credit.

Thibodeau, who along with many Republicans campaigned against sales tax increases in 2010, said he could live with the deal despite their inclusion.

“In any negotiation, you always wish you’d got more,” he said in an interview Tuesday afternoon. “But when you have multiple people involved, every one of us has different priorities. You have to work with the other partners to come up with a package that both of you can be proud of and that you can live with. This does that.”

In the compromise deal, military pensions would be exempted from income tax entirely, and an additional $3.5 million would be exempted from the state’s estate tax, bringing the tax on large inheritances in Maine in line with federal limits.

The Homestead Property Tax Exemption would double, reaching $20,000 by 2017, and Maine’s K-12 schools would receive an additional $40 million in each year of the biennium. Those investments in property tax relief and education were must-have items for Democrats.

“There are a lot of things in here that middle-class Mainers did very, very well by,” Eves said in an interview. “That has always been our objective, and we feel like we’ve accomplished that.”

The House version of the deal also affects the eligibility of legally present noncitizens, such as asylum seekers, for food stamps, Supplemental Security Income and Temporary Assistance for Needy Families by enforcing on them a new eight-month cap on eligibility for those programs. By 10:30 Tuesday night, the Senate had struck that piece of welfare reform from the plan. By that time, it was unclear which chamber would recede to accept the other’s position.

Democrats’ efforts to protect access to General Assistance for the same population of immigrants were left outside the deal in a separate amendment approved by the House but expected to die in the Senate.

Last, the compromise levels the so-called “welfare cliff” by ensuring TANF recipients would not immediately lose all benefits if they have an increase in salary or working hours. Instead, benefits would be phased out as the recipient’s income increases.