Law firm Phillips Lytle LP could become the lead tenant in a revamped and rehabilitated Donovan Building when its current lease in the One HSBC Center tower expires in three years.

Buffalo’s No. 2 law firm confirmed Wednesday that it has been approached by Benderson Development Co. and Ciminelli Development Co. with the idea of relocating to the vacant former state office building, between Main and Washington streets near HSBC Arena.

If it did so, it would likely dominate the eight-story, 146,000 square-foot building, taking up about 60 percent of the space if it maintains its current footprint when it moves.

“The Donovan Building is one of the sites that we have under review, yes,” said David J. McNamara, managing partner of the law firm.

However, he stressed that the firm has made no decision about where to locate, noting it has “no fewer than seven sites under consideration, all in downtown Buffalo,” and has not “expressed or developed a preference for one site over another.”

All of the other sites are currently vacant lots in the central business district, with developers proposing “build-to-suit” construction for the law firm.

McNamara said a lease renewal at its current site is still one option and denied reports that the firm was already certain to leave the HSBC tower, where it has been for decades.

“Nothing could be further from the truth,” he said. “We’re just not at that point in our analysis to have reached that decision.”

Stephen P. Fitzmaurice, chief operating officer of Seneca One Realty LLC, which owns and manages the HSBC tower, said he couldn’t comment on the law firm’s deliberations or lease discussions. “We’re in the midst of negotiations,” he said, citing confidentiality.

Phillips Lytle has been working since at least last June to review its real estate options and possible alternative sites, even hiring national consulting firm Studley Group to help in the process.

The law firm currently occupies 85,000 square feet on six floors in the HSBC tower, but that lease expires in 2013, and officials wanted to see what’s out there before committing to a renewal. Phillips Lytle has 180 attorneys and 425 employees statewide, including 100 attorneys and 325 employees in Buffalo.

Formally known as the Gen. William J. Donovan State Office Building, the 48-year-old downtown edifice has been vacant since early 2007, when the last state offices and employees moved out ahead of a planned demolition.

At the time, the state intended to raze the building, originally to make way for a new transportation center but later as part of the Canal Side redevelopment project that includes the Bass Pro store. However, plans have since changed, and now Benderson — which is overseeing the Canal Side development for the Erie Canal Harbor Development Corp.—plans to keep the frame, gut the interior and redevelop the building.

Aside from staying at HSBC, Donovan is the only existing building or rehab project that the law firm is seriously considering, McNamara said. Other options include building-to-suit on lots at the corner of Swan and Main streets, Seneca and Main streets, and along the Delaware Avenue and Franklin Street corridors between Niagara Square and Tupper Street.

Besides Ciminelli and Benderson, the firm has also received a range of proposals from Uniland Development Co., Ellicott Development Co. and Waterbourne Real Estate. At one time, officials were also evaluating the Cobblestone District, but “our focus has turned to sites more in the central business core,” McNamara said.

He said a decision is likely by the end of the year.