WEST HARTFORD, Conn. - Ralph Nader, barred from even attending the first presidential debate, says he's considering filing a lawsuit against the Commission on Presidential Debates.

Speaking in New London Wednesday night, Nader demanded an apology from the commission. He said he wants the group to donate $25,000 to the Harvard Law School's clinic for electoral reform "or I'll pursue my legal remedies in court."

He repeated the threat to sue while speaking before a crowd of about 1,200 people at Yale University in New Haven Wednesday night. Hundreds of others were turned away for lack of room.

They chanted "Let Ralph Debate!" and held out signs reading, "Don't waste your vote on the corporate candidates!"

"This is the last debate that the debate commission is going to choke off part of America," Nader vowed to a standing ovation.

At a rally earlier Wednesday with 600 people at the University of Hartford, the Green Party presidential candidate blasted "the winner take all, two-party duopoly. He also spoke harshly about Democratic vice presidential candidate Joseph Lieberman, calling him a "political sorcerer."

Speaking to the media, Nader showed off the ticket he obtained for the debate Tuesday night in Boston. But an official from the debate commission stopped him from entering the debate hall, telling Nader he was an uninvited guest.

"This is a political exclusion. They dismissed me for political reasons, not because I was disruptive. I'm never disruptive," he said.

Nader was barred from joining the 90-minute debate between Republican George W. Bush and Democrat Al Gore because he failed to meet the criteria for inclusion. He also was not allowed to watch the debate on television in a nearby room.

"That's got to be the worst mistake the debate commission ever made," Nader said.

Nader said the next step is to form a "people's commission" and get labor groups to sponsor debates that the major party presidential candidates cannot refuse.

A phone message seeking comment was left Wednesday night at the commission's office in Washington.

Meanwhile, in Boston, the 1st U.S. Circuit Court of Appeals scheduled a hearing Thursday before a three-judge panel on Nader's challenge to corporate sponsorship of the debates. The court agreed to an expedited review of his lawsuit, which a lower court rejected last month.

At the Hartford rally, Nader said Gore has enough of a lead over Bush to win the election, and he urged those who consider the Democrats the "lesser of two evils" to vote for him in an effort to make the Green Party a bigger force in American politics. Most polls show the race is close.

In the state they call home, Nader, a longtime consumer advocate, also criticized Lieberman for fighting years ago in the Senate to set a medical malpractice limit of $250,000, accepting corporate sponsorship and supporting weapons programs after the demise of the Soviet Union.

"Attacking Joe Lieberman in Connecticut is unsafe at any speed," said Lieberman spokesman Dan Pfeiffer. "The people of Connecticut have known Joe Lieberman for his entire life and they know him as a man of integrity."

Nader was expected Thursday in his home town of Winsted, Conn.