Rap impresario Russell Simmons (search) is the new toast of Broadway -- but he's in hot water with a state watchdog agency, The Post has learned.

The Tony-award winning Simmons, who helped organize and bankroll a recent rally to repeal the Rockefeller-era drug laws, is under scrutiny by the state Lobbying Commission.

It recently sent him a letter saying he must register as a lobbyist if he has spent more than $2,000 to influence an issue, or explain why not.

"If all he did was come up to Albany and talk to officials on his own behalf, that's OK," said Lobbying Commission executive director David Grandeau.

"If he spent more than $2,000 in furtherance of the lobbying effort, that requires registration," he added.

Failure to register as a lobbyist carries a $25,000 fine. Simmons, who had not seen the commission letter, said: "If we have to register, we will."

The Rockefeller-era drug laws require mandatory sentencing for possession and sale of small amounts of drugs. Opponents of the laws say they target minorities and are too harsh.