ALBANY — Senator Joseph Bruno, the chamber’s Republican majority leader since 1995, said today that he will officially leave office by Friday.

He surprised most in state government last month when he said he would resign but had not given a firm date when he would leave the office he’s held since 1976.

The 79-year-old resident of Rensselaer County near Albany said he would like to return to the private sector and run a business.

State law prohibits him from a lucrative job of lobbying the Legislature for two years.

Senator Dean Skelos, a Republican of Long Island, has been chosen to replace Mr. Bruno, with Mr. Bruno’s support.

In the two years since Governor Pataki left office, Mr. Bruno has been New York’s top Republican leader.

“Frankly, my work is fairly well done,” Mr. Bruno said today at his last major public event, an announcement of an IBM Corp. high-technology project at Albany. “I feel like my transition is done. The furniture is moving out of my office tomorrow, the pictures are off the walls.”

Then Mr. Bruno, true to form, joked: “It can get depressing if I hang around. I push the buttons and nobody’s answering.”

His term would have ended December 31. A general election in November will pick Mr. Bruno’s successor, who will be sworn in in January.

He said his exit doesn’t threaten the Republicans’ majority, now that the regular session is over. The Senate’s Republican majority would likely only convene a special session if there was broad agreement on issues with the Democratic minority.

With Mr. Bruno’s departure, and Democratic Senator John Sabini taking over as head of the state’s Racing and Wagering Board, Republicans will maintain a 31-29 advantage in the chamber they have controlled since the 1960s.

Mr. Bruno leaves behind numerous projects in his home district named for him — such as Joseph L. Bruno Stadium — or which honor him with statues or plaques, such as the bust of him in Albany International Airport. Mr. Bruno steered state and federal funding to numerous projects in his district as well as millions of dollars in pork-barrel spending for local groups, projects and charities.

He has also been part of Albany’s notorious three-men-in-a-room negotiations with governors and the Assembly speaker to agree on state budgets and major policy matters behind closed doors.

“Upstate has never had a more dedicated advocate than they have had in Sen. Bruno,” the Assembly Speaker, Sheldon Silver, a Manhattan Democrat, said.

“He led our conference and the state Senate for 14 years and distinguished himself as one of the greatest leaders in the history of the state,” Mr. Skelos said. “I thank Joe Bruno for his leadership and his friendship and I join millions of New Yorkers in wishing him the very best of luck as he moves forward with the next phase of his life. All of us owe him a tremendous debt of gratitude.”

Mr. Bruno said he’s had eight or nine opportunities presented to him in the private sector since his surprise announcement that he would relinquish the majority leader’s job. He didn’t identify any and said he’s still thinking about how to return to the business world. He ran a telephone company before being elected to the Legislature.

“I’m not the kind of guy who is going to go off and play with horses and golf or whatever else is out there,” Mr. Bruno, who owns horses and still rides, said.

He again told reporters that his decision has nothing to with a two-year-old investigation by the FBI into his consulting and other business ties outside the Senate.

“I am not worried about that,” Mr. Bruno said, noting that he met with his lawyers yesterday. “I have never been charged. There is nothing I could ever contemplate that was inappropriate or illegal.”