Harry Macklowe moved a step closer toward selling his venerable GM Building, receiving what one source described as “several bids” worth more than $3 billion.

However, at least two big-name suitors chose to sit out a second round of bidding for the 50-story tower at 767 Fifth Ave.

Real estate investor Joseph Cayre opted not to file a bid by yesterday’s 5 p.m. deadline. The Post reported Wednesday that SL Green Realty Corp. was also sitting out the second round.

World Trade Center owner Larry Silverstein was described as remaining in the hunt for the building, though there were some rumblings that he might have been put off as a result of a lawsuit filed earlier this week by developer Sheldon Solow, who’s claiming a 2003 sale of the building to Macklowe was bogus.

However, a source familiar with the matter described Silverstein as still “maneuvering and in negotiations” for the tower. He is said to be putting together a bid with California pension fund CalSTRS, though there were suggestions Silverstein might bring in an additional partner for his bid.

Though there is clearly interest in the white marble building that is home to a multitude of hedge funds, law firms and the glass-cubed Apple store in the building’s plaza, there have been doubts raised about whether Macklowe will be able to get just the price he needs for the building.

The debt-laden Macklowe has been hoping to sell the GM Building for at least $3.4 billion in order to pay off debt held by Deutsche Bank and hedge fund Fortress Investment Group.

However, there were doubts earlier this week whether he’d be able to get $3 billion, let alone $3.4 billion. And anything short of the $3.4 billion Macklowe wants raises the chances that he would have to sell other assets in order to meet his debt obligations.

The first round of bids received by CB Richard Ellis brokers Darcy Stacom and Bill Shanahan were said to be just over $3 billion, and earlier this week market sources said they expected second-round offers to be in the range of $2.8 billion to $3 billion.

According to people familiar with the situation, Cayre, who runs real estate investment firm Midtown Equities, decided not to offer any more than $2.8 billion.

All of the parties involved declined comment.