A bill to curb campaign contributions from special interest groups gained a key supporter in the General Assembly today, as figures were released showing the size and number of those contributions have risen dramatically in election years since 1978.

State Sen. Sidney Kramer (D-Montgomery), a member of the Senate committee considering the bill and a candidate for county executive in Montgomery County, announced his support just before a hearing on the bill.

Kramer voted against similar measures in previous years, when the bill has died in committee by one vote.

Kramer was swayed by the fact that spending limits in this bill are more reasonable than limits in previous bills, according to Lanny Davis, Kramer's campaign chairman. Kramer also believes the growth in the number of PACs over the last two years merits imposing "reasonable limits," Davis said.

In the 1978 elections, 50 political action committees were active in Maryland, according to information released today by the lobbying group Maryland Common Cause, and the top 10 groups contributed about $150,000.

During the 1982 election year, the number of PACs swelled to more than 200 and contributions from the top 10 exceeded $500,000, the Common Cause study stated.

Last year, according to the study, PACs donated $269,743 to 128 state legislators in anticipation of this year's elections.

Kramer was the third leading recipient last year with $10,259 in contributions, according to the study, behind House Speaker Benjamin L. Cardin (D-Baltimore), who received $15,190, and state Sen. Dennis F. Rasmussen (D-Baltimore County), who received $13,650.

Cardin recently ended a bid for governor to run for Congress, while Rasmussen is said to be considering a race for county executive in Baltimore County.

Under state law, there are no limits on PAC contributions, as there are for contributions from individuals. Limits on PAC contributions were removed by the General Assembly in 1976 and since then PACs have flourished, according to Common Cause.

This year's PAC bill, sponsored by state Sen. Gerald W. Winegrad (D-Anne Arundel), would limit gubernatorial candidates to a total $20,000 contribution from PACs; county executive and mayoral candidates to $10,000; and candidates for other offices to $3,500.

The political action committees would be limited to a maximum of $1,000 in contributions per candidate and would be barred from setting up multiple committees, according to the bill.

The bill's supporters, led by Common Cause, were buoyed by Kramer's announcement.

"I think elections this year have everything to do with this issue," said Ricki G. Wadsworth, executive director of Common Cause. "I think these members will look at this issue differently this year."

Wadsworth said Kramer's decision vastly improved the measure's chances for favorable committee action, which would allow the full Senate to vote on it for the first time since the measures were first introduced in 1983.

But opponents vowed to kill the bill again, calling it a threat to the democratic process.

"This bill is dead," said Bruce Bereano, an Annapolis lobbyist who manages PACs on behalf of state cemetery owners, the tobacco industry and three other special interest groups.

Meanwhile, state Senate President Melvin A. Steinberg (D-Baltimore County) reacted coolly to the measure. "The key is disclosure," he said in an interview. "I believe in special interests."