AUGUSTA –– Legislative leaders scheduled another full weekend of talks to reach a deal over the state’s next two-year budget after a week of fits, starts and a blowup in which the negotiators blamed one another for bringing the state to the brink of a government shutdown.

The full Legislature is expected to begin voting Monday on a budget agreement that was ratified last week by the Legislature’s Appropriations and Financial Affairs Committee but lacks Republican support and will need amendments to gain final passage. The substance of the amendments will be the focus of this weekend’s negotiations.

Meanwhile, political forces outside the State House advanced campaigns to influence the budget talks and public opinion on the issue.

On Friday, a progressive group aligned with the Maine Democratic Party launched a series of ads and automated telephone calls that accused House Republican leader Kenneth Fredette of Newport and Gov. Paul LePage of trying to shutter the government. The Maine Republican Party and aligned interest groups began running their own messaging campaign, taking to newspaper columns and press statements that lay the blame on Democratic House Speaker Mark Eves of North Berwick.

The campaigns underscore the significance of the spending plan being discussed in private. The two-year budget has become the singular focus of a legislative session in which neither the Republican-controlled Senate nor the Democratic-controlled House has been able to claim many policy victories. The same is true of LePage, who won decisive re-election in November but has seen the majority of his conservative policy initiatives fall into the chasm of divided government.

The budget stands as the one piece of legislation in which all sides have the chance to claim something of a victory from a legislative session marked by partisan votes, gubernatorial vetoes and abandoned efforts to reach a compromise.

Compromise on the budget, however, isn’t an option. It’s necessary to keep the state running. The Maine Constitution requires the state to have a balanced budget.

Two weeks ago, Eves and Senate President Mike Thibodeau, R-Winterport, as well as Senate Minority Leader Justin Alfond, D-Portland, reached a budget deal that has since been ratified by the majority of the Legislature’s budget-writing committee.

As of Friday, Eves and Thibodeau were planning to bring the budget agreement to floor votes as soon as Monday. Both leaders acknowledge that the plan doesn’t have enough support to attain a two-thirds vote, which is necessary to override a veto by LePage. However, they hope that the weekend negotiations will yield a compromise that will allow them to tack on amendments from the floor of the House or Senate.

The amendments are necessary because Fredette, backed by the governor, has led a rebellion against the original agreement. He has pushed for income tax cuts and changes to the state’s General Assistance program. Fredette’s efforts appear to have won him the support of his conservative caucus. However, it’s also made him an easy target for those assigning blame for a shutdown.

Nonetheless, income tax cuts appear to be back on the negotiating table. How the cuts are paid for and which Mainers benefit continue to be the primary sticking points.

Eves has argued that Fredette’s tax plan, represented in the minority report of the budget committee, will mostly benefit high-income earners. His argument has been backed by a memo from Maine Revenue Services, which conducted an analysis of the Republican tax initiative and found that it was “heavily weighted at the top end.”

“Democrats are at the table fighting for a budget that will grow our economy from the middle out,” Eves said in a statement Friday. “We want targeted tax cuts and property tax relief that gives most of the benefit to middle- and low-income families, while investing in education and job training for workers and students. We reject the trickle-down economics that has widened the gap between the rich and the poor in our state and country.”

Fredette, meanwhile, has echoed the governor’s call for an income tax cut and welfare reform.

“I’m pleased negotiations are continuing on the budget as we all strive to find common ground,” he said in a statement issued Friday. “We plan to work throughout the weekend and it is my hope we can continue to do so in a productive manner and craft a budget that is in the best interest of the people of Maine.”