ALBANY — Governor Spitzer’s former communications director refused today to testify or provide information under a subpoena issued by a Senate committee investigating an alleged plot to smear the state’s top Republican.

“So much for ‘full cooperation,'” a Senate investigations committee chairman, George Winner, said of the move by a former aide to Mr. Spitzer, Darren Dopp. “The governor clearly told him not to provide any information and assert certain privileges and he said, ‘Yes, sir.'”

Mr. Winner, a Republican senator from Elmira, said Mr. Dopp could face a misdemeanor charge of contempt of the Legislature.

“We are happy to testify and it’s not our privilege that we’re concerned about, it’s the governor’s privilege that we were asked to honor,” Mr. Dopp’s lawyer, Terence Kindlon, said.

Mr. Kindlon said he was advised by a lawyer for the governor that the information Mr. Dopp had about the executive chamber was privileged.

He said a state judge should determine whether the information is privileged, and his client would comply with that decision.

Attorney General Cuomo reported in July that Mr. Dopp and at least one other top Spitzer aide used state police to compile travel reports on the Senate Republican leader, Joseph Bruno. The data tracked Mr. Bruno’s use of state aircraft and a state police driver on days he attended Republican fundraisers after meeting with lobbyists. The travel records were then provided to a newspaper reporter who had requested them.

A subsequent investigation by the Albany County district attorney, P. David Soares, found no wrongdoing and no plot to smear Mr. Bruno. The Senate investigations committee and the state Public Integrity Commission continue to investigate the case, which has led to gridlock in Albany since early summer.

A letter from Mr. Kindlon was delivered to the committee as it prepared to question Mr. Dopp and receive e-mails, private e-mail accounts, and other documents.

“We reminded everyone on the record of the provisions of the penal law involved in contempt of the Legislature,” Mr. Winner said. “Our next step is either to enforce this on our own, or fold it into other litigation that’s going on with the governor’s office.”

Mr. Spitzer is fighting the Senate committee’s subpoenas. The Democratic governor has said the hearings run by Republican Senators are politically motivated.

“The stonewalling continues, notwithstanding the promises of transparency,” Mr. Winner said. “It just belies the facts.”

There was no immediate comment from Mr. Spitzer’s office. Mr. Spitzer said he is fully cooperating with the integrity commission probe as he did with the investigations by Messrs. Cuomo and Soares, both of whom are Democrats.