BATON ROUGE, La. (AP) _ After outlining legislative programs designed to pay off Louisiana's ballooning deficit, Gov. Buddy Roemer has conceded that he's going to have to scale down some of his proposals.

During the first three weeks of the annual session, legislators have grilled the new governor's budget officials and questioned whether his budget is balanced. The House also watered down one of the governor's key legislative programs - tightening up campaign finance laws.

Roemer has proposed a $7.8 billion state budget for the new fiscal year, down from the $8.1 billion plan approved for the 1987-88 fiscal year.

During his campaign, Roemer had ambitious plans for economic development, for revamping the state's tax system and for improving education and the environment.

He believed then that the state faced a $150 million shortfall. However, when he took office two months ago, he found he had inherited a $2 billion crisis.

Shortly before his inauguration, he said his role as governor would have to combine the two roles of crisis manager and long-term planner.

''They (legislators) know we've got a lot of work to do and it can't be all my way. I don't expect that,'' Roemer said. ''But I wanted us to get off the mark and get to work on these problems together.''

One of the trickiest issues facing the new governor is how to reach his goal of weaning local governments and school boards from state subsidies that now total more than $400 million a year.

During Louisiana's populist history, the state has appropriated money for supplemental pay for police and firefighters and parish road funds. It has also paid for school bus drivers and school cafeteria workers.

Following meetings with mayors, demonstrations at the Capitol by school employees and criticism from lawmakers, Roemer said last week that some type of ''bridge funding'' would be provided for the next fiscal year.

However, he didn't say how much the funding would total - or where it would come from.

Roemer added about $95 million to his budget last week to restore a planned 10 percent pay cut for state employees and keep a charity hospital open as a clinic.

To make up part of the difference, most state agencies would take an additional 3 percent across-the-board cut in administrative costs, and patients at state charity hospitals would have to pay a small fee for each visit.

Although the Roemer administration has maintained that the proposed budget is in balance, it has acknowledged that the budget overlooks a projected $260 million loss in state sales taxes.

Rep. Raymond Laborde, a former floor leader for Gov. Edwin Edwards, who was ousted last fall by Roemer, said, ''I don't think this budget is balanced. I don't think the governor thinks this budget is balanced. I don't think the governor's people think this budget is balanced.''

Last week, the House refused to go along with many of Roemer's proposals to tighten up campaign finance laws, although it did approve some restrictions on contributions.

The governor wants a law in which all cash contributions are outlawed and candidates must report 10 days in advance the amount of money they'll be doling out for ''get-out-the-vote'' efforts on election day and who will receive that cash. The House refused to go along with those proposals.

During his campaign, Roemer limited individual contributors to $1,000 and took no money from political action committees.

Under the measure that finally emerged from the House, no candidate for statewide office could receive more than $5,000 from any individual or from any political action committee.

''They put some limits on individual contributions. They limited PACs which you know is important to me,'' Roemer said. ''They've got some things I wish weren't in there, but they've made a step forward.''