The Maryland General Assembly gave final approval Monday to the state’s $13.8 billion operating budget, which relies heavily on federal economic help to avoid even deeper cuts during uniquely troubling financial conditions.

The Senate approved changes to a compromise budget on the last day of the legislative session. The House already has signed off on the legislation, which includes about $866 million in spending reductions and relies on more than $1.5 billion in federal help to the state’s baseline budget.

Democrats said the budget maintains spending priorities for education and health, leaving in place money to maintain an in-state tuition freeze at public colleges and universities and full funding for plans to compensate school districts where education costs more.

“Despite the challenges ... we have been able to preserve many key priorities,” said Sen. Ulysses Currie, the Prince George’s County Democrat who chairs the Senate Budget and Taxation Committee.

The budget maintains a $96 million budget cushion, which was short of aims earlier in the session to put aside at least $200 million in fund balance. The state also has about $750 million in rainy-day reserves.

Republicans criticized the degree of reliance on federal help, saying the state is setting itself up for serious pain if the economy doesn’t have a big turnaround by next year.

Sen. Allan Kittleman, R-Howard, asked Currie if the state will have to find $1.5 billion in new revenue in two years in order to keep the same level of spending.

Currie replied: “Yes, and hopefully the economy will have gone up beyond where we are now.”

Republicans did not find that answer reassuring.

“Well, Mr. Chairman, I hope the economy goes up as well, but we certainly can’t bank on that,” Kittleman said.

The budget process has been unusually complicated this session. Besides figuring out how federal stimulus money could be used to address Maryland’s budget woes, lawmakers also had to factor in a dizzying $1.2 billion drop in revenue estimates last month.

Lawmakers decided to fill a large hole in the budget by using bonds instead of cash to buy public land in the state’s Program Open Space, which uses part of the state’s real estate transfer tax to buy public land. About $140 million in cash will be replaced with bonds. Lawmakers also made up a big part of the budget shortfall by cutting $162 million in local road maintenance.

The Senate held a lengthy debate on plans to use about $2 million from the state’s public campaign financing fund for a new voting system with optical scans of paper ballots. Republicans decried the move, saying it would was a calculated move to hurt a Republican candidate who may need the money in a run for governor against a Democratic incumbent.

“This is the first time I’ve seen in seven years a direct money grab for the next election that protects an incumbent governor,” said Sen. E.J. Pipkin, R-Cecil.

Currie said lawmakers have been forced to shift money from many sources to address serious budget problems.

“We’ve never been here before,” Currie said. “These are very tough times. These are times similar to the Great Depression.”

Republicans, the minority party in a state where registered Democrats outnumber Republicans 2-1, have been sensitive to the use of the fund, because plans in the House called for using another $2 million from it to pay to get early voting started in Maryland. Sen. Roy Dyson, D-St. Mary’s, said there were no plans to use the campaign fund to pay for early voting.

Meanwhile, House and Senate negotiators continued to struggle on how to handle licenses for illegal immigrants, with less than six hours left in the legislative session. The House has approved letting illegal immigrants who already have licenses renew them and receive a separate ID. But the Senate version of the bill would not allow illegal immigrants to have a driver’s license at all.

On environmental matters, lawmakers sent a bill that seeks to reduce Maryland’s greenhouse gas emissions by 25 percent by 2020 through recycling and renewable energy to O’Malley for his signature. The bill failed last year after business and labor organizations feared it would hurt manufacturing jobs, but the measure was changed this year to ensure no manufacturing jobs would be lost because of the legislation. The bill requires the Maryland Department of the Environment to adopt a final greenhouse gas emissions reduction plan by December 2010.

In another high-profile issue, the House has given final approval to legislation designed to strengthen Maryland’s ability to keep the Preakness Stakes horse race in the state. The bill would give Maryland eminent domain authority to keep the Triple Crown’s second leg in the state. The future of the famous race has been called into question because of federal bankruptcy proceedings involving current owner, Magna Entertainment Corp.

In other business, the Senate advanced a bill to ban people from sending text messages while driving to Gov. Martin O’Malley, who supports the ban. The Senate decided to approve the measure with an amendment by the House of Delegates, a change that will still allow people to read text messages that are sent to them. Writing or sending text messages, however, would be banned while driving.