Virginia Democrats are attempting to use the state budget to win back power in the evenly split state Senate, threatening to hold up the $85 billion spending plan if Republicans don’t relinquish some of the power they claimed at the start of session.

The attempted power play comes halfway into a General Assembly session in which Democrats have been largely powerless to stop the GOP’s conservative legislative agenda because Lt. Gov. Bill Bolling could break most tie votes.

Now, because Bolling (R) does not have authority to vote on budget matters, the Democrats have some sway. Using the prospect of a deadlocked Senate as leverage, Democrats are trying to beef up their influence on crucial committees, where the fate of legislation is largely decided.

Senate Minority Leader Richard L. Saslaw (D-Fairfax) and Sen. A. Donald McEachin (D-Henrico) laid out their demands in a letter they had hand-delivered Friday to Senate Majority Leader Thomas K. Norment (R-James City).

The Democrats’ proposal falls short of the full power-sharing deal they’d sought after the November elections left the chamber evenly divided between the two parties. But it would give Democrats more say on some key committees, which Republicans were able to stack in their favor with help from Bolling’s tiebreaking votes.

In their letter, Saslaw and McEachin called it “a reasonable proposal for the committee structure of the Senate.”

Norment publicly dismissed the Democrats’ effort this week in a letter of his own, which also referenced recent communication between the Democrats and Gov. Robert F. McDonnell (R) about the budget.

“In your joint letter to the Governor of last Wednesday, you articulated that ‘our concerns about the budget are not partisan, but substantive,’ ” Norment wrote. “Particularly in light of that assertion, it was disheartening to read your letter and see there were absolutely no policy concerns expressed, only raw partisan, political objectives having absolutely nothing to do with the budget. Intellectually, and as a good steward of the Commonwealth, I cannot link the budget to partisan, political pressures.”

But Saslaw said the effort was akin to the ordinary horse-trading that goes on during any General Assembly session.

“It’s all part of the system,” he said.

As Senate Democrats attempt to leverage their newfound muscle for more committee power, their counterparts in the House of Delegates hope only to amend the budget approved Sunday by the House Appropriations Committee.

The committee had added millions of dollars for schools, local governments and health care, but that still fell far short of what Democrats desired. Northern Virginia Democrats were particularly concerned that the committee had not restored any of the $65 million in “cost-of-competing funds,” which McDonnell eliminated from his spending plan. The funds are usually provided to Northern Virginia school districts to woo employees in the expensive job market. McDonnell’s proposed budget includes the funds for teachers, but not for other school staff.

At a meeting of the Northern Virginia legislators Monday, House Democrats vowed to try to round up the votes needed to add cost-of-competing funds to the budget. But they acknowledged it would be a nearly impossible task; Republicans outnumber Democrats 67-32, with one independent who caucuses with Republicans.

Democrats on the House side said they’d gladly take the budget the Senate Finance Committee agreed to on Sunday, adding millions for schools and social services and spurning McDonnell’s plan to divert general fund revenues away from education and other core services and toward transportation.

But funding still falls short of what some Senate Democrats would have liked. The Senate Finance Committee’s plan would, for instance, restore $42 million of the $65 million in cost-of-competing funding. But some Senate Democrats continue to push for the full $65 million.

On the floor of the Senate on Tuesday, Sen. Ryan T. McDougle (R-Hanover) ticked off many of the programs Republicans had agreed to better fund at the request of Democrats. After responding to Democrats’ budget concerns, Republicans said Democrats were wrong to try to use the budget process to grab more power on committees, where the fate of legislation is largely decided.

Saslaw and McEachin have asked that more Democrats get appointed to certain committees, that some Republicans get removed, and that leadership of the powerful Senate Finance Committee be split between Republican and Democratic co-chairs.

Their proposal would affect six of the 11 Senate committees, which Democrats had controlled for four years. Every committee would continue to be chaired by Republicans, with the exception of the co-chaired finance committee.