The Major League Baseball Players Association would not commit today to any meeting between Giambi and Mitchell.

"Jason will determine how to respond to the commissioner's request ... after consulting with MLBPA counsel and his own lawyer," union general counsel Michael Weiner said.

Selig deferred a decision on whether to discipline Giambi for recent remarks that many interpreted as an admission of steroids use.

Selig had been deliberating since May 23, when Giambi met with lawyers from Major League Baseball. Selig will take Giambi's level of cooperation into account.

"Any admission regarding the use of illegal performance-enhancing substances, no matter how casual, must be taken seriously," Selig said. "It is in the best interests of baseball for everyone, including players, to cooperate with Senator Mitchell in his investigation.

"Discipline for wrongdoing is important, but it is also important to create an environment so players can feel free to honestly and completely cooperate with this important investigation."

Mitchell, a former Senate Majority Leader, has been investigating steroids since he was hired by Selig in March 2006.

Giambi told a federal grand jury in December 2003 that he used steroids and human growth hormone, the San Francisco Chronicle reported in December 2004. Before the start of spring training in 2005, the former AL MVP made repeated general apologies at a news conference but never used the word "steroids."

The designated hitter, on the disabled list with a foot injury, told USA Today in comments published May 18: "I was wrong for doing that stuff.

"What we should have done a long time ago was stand up — players, ownership, everybody — and said: 'We made a mistake,"' he said.

According to the union, penalizing Giambi would also be a mistake.