New York Yankees third baseman Alex Rodriguez may be suspended for admitting he using performance-enhancing drugs, Commissioner Bud Selig told USA TODAY on Wednesday.

Selig and MLB officials realize any attempt to suspend Rodriguez would be challenged by the players association since the penalty phase of baseball's testing policy was not implemented until 2004. Yet, Selig said he sent a memo banning steroids around 1997, and that it was illegal to possess them without a prescription.

"It was against the law, so I would have to think about that," Selig told USA TODAY's Christine Brennan in his first comments since Rodriguez's admission. "It's very hard. I've got to think about all that kind of stuff."

Rodriguez would be the first player to serve a suspension without testing positive during the program's penalty years.

"I would be surprised if there was an attempt to do it," said Don Fehr, the union's executive director.

Rodriguez tested positive for steroids during 2003 anonymous survey testing, Sports Illustrated reported. Rodriguez confirmed Monday in an ESPN interview that he used banned substances from 2001 to 2003. Several players have admitted using steroids or human growth hormone but were not suspended.

"This is serious stuff. We all know that," Yankees general manager Brian Cashman said. "No one can wave a magic wand and make it all go away."

Selig said he also is considering reinstating Hank Aaron as baseball's home run king in the record book. Barry Bonds broke Aaron's record of 755 home runs in 2007 but is scheduled to stand trial March 2 on charges he lied to a federal grand jury about performance-enhancing drugs.

"This is breaking my heart. I don't mind telling you that," Selig said.