AUGUSTA — House Republicans have entrenched themselves against the rest of the Legislature — including their fellow GOP Senators — and are vowing to fight a state budget being crafted in the Legislature because it doesn’t include income tax cuts or welfare reforms favored by Gov. Paul LePage.

Meanwhile, Senate Republicans said they have forged a major deal with Democrats to make future income tax increases much more difficult than they are now.

Democrats and the two Senate Republicans on the Appropriations Committee banded together late Sunday night to unravel some of LePage’s top policy priorities, including voting down welfare reform initiatives, killing proposals to reduce the income tax rate and scaling back the governor’s goal to add more drug enforcement personnel. The votes were preliminary and won’t be final until the budget committee finishes its work.

House Minority Leader Ken Fredette of Newport and Rep. Ellie Espling of New Gloucester said they won’t support any budget that doesn’t include major elements from LePage’s budget.

“House Republicans want to stand on the principles that are important to the Republican Party, such as smaller government, welfare reform and income tax cuts,” said Fredette. “I will fight tooth and nail to defeat a majority budget on the House floor so that we can bring that budget back [to the Appropriations Committee] to have a meaningful conversation.”

If House Republicans hold to that view, then enactment of a state budget — which at this point requires two-thirds votes of both the House and Senate — is impossible. Failure to enact a budget by June 30 would result in a state shutdown — which is something everyone says they want to avoid.

“If income tax cuts can be a serious part of the conversation, we still have some time,” said Espling. “That can still be considered.”

Meanwhile, Senate Republicans claimed they have scored a major victory that will be the focus of debate in the coming days. Republican Senate President Mike Thibodeau of Winterport and Senate Majority Leader Garrett Mason of Lisbon said they have a deal with Democrats to support a constitutional amendment that would require a two-thirds vote in the Legislature for any future income tax increases. Currently, that requires only a simple majority.

“This would be monumental in moving our state forward,” said Thibodeau. “This is a very, very big opportunity to do something good for our state. Having a two-thirds vote of either chamber for something like this is not easy.”

The announcement by Thibodeau and Mason came after a weekend filled with mostly waiting. After hours of behind-the-scenes negotiations, the Appropriations Committee convened after 11 p.m. Sunday and voted down a range of proposals that came straight from LePage:

— They watered down LePage’s plan to fight the proliferation of illegal drugs. LePage proposed funding for seven new Maine Drug Enforcement Agency investigators; the committee amended that down to four new state-funded agents. LePage proposed creating 22 new assistant district attorney positions; the committee amended that number down to ten. And finally, LePage proposed creating four new district court judges to deal with drug crimes; the committee amended that down to two new judges and two new legal clerks to support them.

— LePage proposed — and has for years tried to achieve — reducing funding for undocumented aliens in the Temporary Assistance for Needy Families and Supplemental Nutrition Assistance Programs; the Appropriations Committee voted that down.

— The committee voted against LePage’s proposal to bar undocumented and illegal immigrants from the General Assistance program, which is administered at the local level but partially funded by the state.

On most of those votes, the four House Republicans on the committee — Rep. Jeff Timberlake of Turner, Rep. Tom Winsor of Norway, Rep. John Nutting of Oakland and Rep. Heather Sirocki of Scarborough — voted together. Republican Sens. Roger Katz of Augusta and James Hamper of Oxford voted with the Democrats, leading to angry comments by Timberlake.

“After sitting on this committee for the past six months and hearing the drug problems we’re having in this state, I couldn’t possibly understand for a second why we would want to cut back on seven investigatory drug agents,” he said before the vote on the MDEA agents. “I will be voting against this.”

House Speaker Mark Eves, D-North Berwick, said his priority is avoiding a budget impasse and a government shutdown. He said Democrats won’t support LePage’s and Republicans’ income tax cuts unless they are aimed at the middle class and not upper earners.

“Those that are willing to stand in the way of a fair, responsible budget, it’s unacceptable,” said Mark Eves. “We will not give a tax giveaway to the rich.”