Developer Sheldon Solow has thrown what he believes is a wrench into the current Macklowe Properties’ sale of the GM Building, filing a lawsuit contending that former owner Conseco never officially sold the trophy tower to Harry Macklowe in 2003.

The complaint, filed in state court, alleges the original auction to sell the building on behalf of Conseco was a sham that ensured Macklowe won. As such, the suit argues, the building’s still owned by Conseco.

Solow is not in the current round of bidding for the 50-story tower because he thinks Macklowe doesn’t own it. Final bids are due today.

Macklowe spokesman Steve Solomon said the suit is “totally without merit.”

The suit was filed against defendants including a Conseco employee, real estate broker Eastdil Secured, Wayne Maggin, the Eastdil agent who conducted the auction, and Macklowe, who allegedly had been advised to “pre-empt” the auction.