After weeks of pitched battles over guns, abortion and voting rights, the Virginia General Assembly is about to fight over something else: money.

The Senate Finance and House Appropriations committees will release their versions of the state budget Sunday after having their way with Gov. Robert F. McDonnell’s two-year, $85 billion spending plan.

Along with the shift in focus comes a power shift, as Democrats see their opportunity to come roaring back in Richmond.

The budget proposed by McDonnell (R) would move millions from public schools and health care to higher education, transportation and the underfunded state pension system. Legislators have the power to overhaul his 483-page plan. And while they don’t seem inclined to go that far, they intend to do more than tweak it.

House and Senate leaders said they will increase money for K-12 education and boost funding for free health clinics, nursing homes and hospitals. They intend to restore some cuts to localities.

The tax-averse House also wants to strip McDonnell’s proposed budget of $22 million in higher Department of Motor Vehicles and restaurant inspection fees and increased employer payments to the unemployment compensation trust fund.

“There will be some changes” in the budget, Sen. Charles J. Colgan (D-Prince William) said.

That’s an understatement when it comes to transportation, at least in the Senate.

The House has largely endorsed McDonnell’s plan to divert $110 million from the general fund, which pays for core services such as education and health care, to spend on transportation. But the Senate balked, instead proposing a plan that would raise the gas tax to reflect inflation.

“I rather suspect the governor was surprised when it was dumped on top of his transportation bill,” said Sen. Mark D. Obenshain (R-Harrisonburg), who predicted the gas tax increase would not pass the House.

Democrats have been shut out of power since Republicans, who already had the House and governor’s mansion, took control of the evenly divided Senate in January. The GOP could claim the majority because Lt. Gov. Bill Bolling (R) has the power to break tie votes.

But Bolling has acknowledged that he does not have authority to vote on budget matters. So Democrats, at least in the Senate, suddenly have some muscle to flex.

Republicans have warned Senate Democrats against playing politics with the budget. Senate Majority Leader Thomas K. Norment (R-James City), a member of the Finance Committee, said there is little reason for them to do so; the committee is likely to amend McDonnell’s budget to make it more amenable to Democrats.

“We are putting things in the budget that they have asked for, perhaps that Republicans might not otherwise embrace,” Norment said. “I would just hope they don’t turn around and say, ‘Our political feelings are still hurt, and therefore we’re going to vote against a budget . . . to show that we’re politically relevant.’ ”

Sens. Richard L. Saslaw (D-Fairfax) and A. Donald McEachin (D-Richmond) dashed off an angry letter to McDonnell on Thursday after the governor released one he’d sent them to ask for Democratic budget proposals.

“[Y]our release of your letter without waiting even twenty-four hours for a response smacks of gamesmanship and not of an effort to resolve our differences,” they wrote.

Even if Senate Republicans and Democrats can find common ground, they’ll have to reconcile their budget with the one that comes out of the more conservative House before the General Assembly adjourns March 10.

But right now, the chambers are focused on fleshing out their separate plans.

House Majority Leader M. Kirkland Cox (R-Colonial Heights) said the House plan will include fewer tax credits than McDonnell recommended.

On health care, House and Senate budget writers are looking to restore some cuts. McDonnell made his deepest cuts in Medi­caid, saving $259 million by not adjusting hospital payments for inflation. He also sought to cut health-care safety net providers by 50 percent in the second year of the budget — a total of $4.8 million from free clinics, community health centers and the Virginia Health Care Foundation.

“I think they’re very concerned about health care,’’ said Katharine Webb, senior vice president at the Virginia Hospital and Healthcare Association. “I’m hopeful and optimistic the case has been made.’’

McDonnell proposed an increase of $438 million for K-12 education. But $342 million of that would go to replenish the teacher retirement system. He also recommended withholding inflation adjustments for any non-teaching expenses.

Lawmakers said they plan larger increases in K-12 funding, with the House pegging its figure at $140 million and the Senate not disclosing how much it would add.

Both chambers support McDonnell’s proposal to spend $230 million on colleges and universities. But House Republicans say they will reduce some of the money McDonnell allocated for research and development.

McDonnell has proposed pumping a record $2.2 billion into the state retirement system for state and local employees over the next two years.

House and Senate leaders support that but object to some changes he has made for retiree benefits.