Never invited to appear was another star who testified to that grand jury, Barry Bonds, who broke McGwire's season record by hitting 73 homers in 2001 and is approaching Hank Aaron's career mark of 755.
Selig and union head Donald Fehr were to appear, along with baseball executive vice presidents Rob Manfred and Sandy Alderson and San Diego Padres general manager Kevin Towers.
Punishments that members of Congress already had called too weak were criticized further Wednesday when the committee released the draft testing agreement and pointed out that it retains a provision that allows the commissioner to substitute fines for suspensions. A player could be docked $10,000 instead of receiving a 10-day ban for a first offense, for example.
Manfred responded that players would be suspended in all instances for positive tests.
Davis and Waxman wrote to Selig and Fehr.
"Even if players are suspended, the public disclosure is limited to the fact of their suspension with no official confirmation that the player tested positive for steroids," they said. "In contrast, the Olympic policy calls for a two-year suspension for a first offense."
They also said the deal didn't prohibit four steroids banned by the World Anti-Doping Agency, calling it a "significant omission."
Canseco, who retired in 2001 with 462 homers, asked for immunity so he could testify fully, but that request was turned down Wednesday. It was his book that brought a lot of attention to the issue; he wrote that he used steroids and that he injected McGwire with them. McGwire has denied using performance-enhancing substances.
The committee started by inviting witnesses -- with no luck. So the panel issued subpoenas, compelling the players and others to show. Major League Baseball said it would fight the subpoenas; Davis and Waxman responded by threatening contempt of Congress charges.
