Washington ? A major league baseball official urged Congress on Tuesday to regulate substances such as androstenedione, the over-the-counter supplement Mark McGwire used the year he broke the single-season home run mark.

Rob Manfred, baseball’s executive vice president for labor relations, made the suggestion at a Senate hearing examining the use of steroids in baseball.

Donald Fehr, executive director of the Major League Baseball Players Assn., agreed it might be time for Congress to look again at andro, which, like illegal steroids, helps the body create testosterone.

While the players association and baseball seemed close to agreeing on andro, they diverged sharply on whether players should be tested for steroids.

Baseball is under scrutiny after former National League MVP Ken Caminiti admitted using steroids and estimated that half of the sport’s players do as well. Former American League MVP Jose Canseco said up to 85 percent took steroids. Both players declined invitations to testify Tuesday.

Sen. Byron Dorgan, D-N.D., who chaired the hearing of the Senate Commerce subcommittee on consumer affairs, said it was too soon to say whether Congress would follow up with legislation.

“It’s a complicated topic,” said Dorgan, whose former chief of staff, Lucy Calautti, is now baseball’s lobbyist. “There are so many substances where does one start?”