The Virginia Senate failed to pass its version of the state’s two-year, $85 billion budget Thursday afternoon after all the chamber’s Democrats voted against the bill in a dispute over power-sharing.

The Senate voted 20 to 17 for the budget plan, but 21 votes — a majority of those elected to the 40-member body — are required for passage.

Democrats have tried to use the state budget to regain power in the evenly split Senate, which Republicans have been able to control with help from Lt. Gov. Bill Bolling’s tie-breaking votes.

Because Bolling (R) lacks authority to vote on budget matters, Democrats attempted to use the prospect of a deadlock on the budget to push for a power-sharing deal that Republicans had rejected in January.

Democratic Senate leaders last week asked the body’s majority leader, Thomas K. Norment Jr. (R-James City), to give them more seats on crucial committees. Norment rejected the deal. So on Thursday, Democrats refused to vote for the budget. Afterward, Republicans excoriated Democrats for blocking the budget.

“Passing a balanced budget, on time, is the most important duty of all of us sent to Richmond,’’ Gov. Robert F. McDonnell (R) said. “Now, for apparently partisan reasons, Senate Democrats may have put a timely budget at risk. . . . This is not the Virginia way.”

Said Norment: “The ‘no’ vote was the result of them having political-bruised egos going back to day one, when they did not get what they felt was a fair distribution of the committee assignments.”

Bolling called the outcome “a very disappointing day for the people of Virginia. . . . For them to vote against the budget is just an incredible exercise in political hypocrisy. And by casting a vote against the budget, Democrats now stand as obstructionists.’’

Sen. A. Donald McEachin (D-Richmond) said the Democrats were not playing politics with the budget.

“Our ‘no’ vote today was not about politics,” he said. “It’s about people. If the Senate really reflected the will of Virginia’s voters, we wouldn’t see a budget like this.’’

The House passed its version of the budget with a 79 to 21 vote, with 11 Democrats voting for the budget.

“The House budget is a structurally, substantively and fiscally responsible plan,’’ Speaker William J. Howell (R-Stafford) said.

Senators said they will act on that bill next week, but there’s no guarantee that the Democrats will vote for that one, which provides less money for schools, social services and other Democratic priorities than the Senate version.