The Maryland Republican Party did not violate state law when it launched a $25,000 radio and newspaper advertising campaign in January to dissuade three key Democratic senators from overriding the vetoes of Gov. Robert L. Ehrlich Jr. (R), the state attorney general's office ruled yesterday.

Democrats had alleged the advertisements violated state lobbying laws, which require anyone spending more than $2,000 to influence legislation to register as a lobbyist.

"In our opinion, a political party recognized by and regulated under the State Election Law is not required to register as a lobbyist," stated the May 27 opinion, which was signed by Attorney General J. Joseph Curran Jr. (D).

A state Republican Party official released a statement yesterday saying the opinion "vindicates the GOP."

The ad campaign interchangeably named three state senators from Anne Arundel County, accusing them of supporting "raising taxes on Maryland's small businesses."

The ads ran during a divisive debate over two bills that had been vetoed by Ehrlich. One was aimed at reducing malpractice premiums for doctors. It passed during a special legislative session in December over objections from the governor, who disapproved of the plan to finance the reduction with a 2 percent tax on HMO premiums. The other, which increased funding for higher education and imposed a cap on tuition costs, was funded with a half-percent increase in the state corporate tax.

Lawmakers overrode the governor's veto of the medical malpractice bill. Ehrlich's decision to increase higher education funding headed off an override of the tuition cap proposal.

Democrats said yesterday that, regardless of the attorney general's ruling, they believe the advertising campaign backfired.

"Quite honestly, they did me a favor," said Sen. John C. Astle (D-Anne Arundel), who was one of those targeted by the ads. "When you come out and attack someone like they did, it really turns people off."