Gov. Bob McDonnell (R) has written a letter to Senate Democrats urging them to work on — and pass — a state budget.

McDonnell (R) outlined a series of problems that would occur if the General Assembly did not pass a budget before the fiscal year begins July 1: Cash-strapped schools would not have state funding, Virginia would fail to meet the requirements of its legal agreement with federal authorities to care for the developmentally disabled, and residents would face a tax increase because local personal property taxes on cars would not be reimbursed.

“The only conclusion that the public can now reach is that your opposition to the budget is solely for political reasons,’’ McDonnell wrote. “I understand your caucus is upset about individual committee assignments. However, any disagreement in this regard should have had no bearing on the passage of the most important legislation of the session: the budget bill. Nonetheless, that is what happened.’’

The Senate killed two previous budgets after all 20 Democrats voted against the spending plans in a bid for more power in the equally divided chamber

The House of Delegates voted Friday afternoon for a third two-year $85 billion budget.

Legislative leaders said Friday that if the Senate does not pass that budget, the General Assembly will not finish its work by next Saturday’s scheduled adjournment. They could either extend the 60-day session or come back for a special session.

Leaders of both chambers gathered for a Friday afternoon news conference to talk about the situation.

“It is all about raw political power,’’ House Speaker Bill Howell (R-Stafford) said. “They’re holding the commonwealth hostage.”

Democrats have said their opposition has had more to do with teacher pay, tax breaks for private schools, tolls and traffic, and bills that force additional burdens and costs on women seeking abortions.

“I am disappointed in the partisan rhetoric of my Republican colleagues. They’re saying what’s theirs is theirs and what’s ours is negotiable,” said Sen. Mark Herring, D-Loudoun.

About 45 law enforcement officers from across the state watched the General Assembly at work Friday to remind legislators about the need to pass a budget.