BOSTON -- Green Party presidential candidate Ralph Nader has booked the FleetCenter for a political rally to be held two days before the scheduled presidential debate at the University of Massachusetts' Boston campus.

The focus of the rally will be the "closed-door" nature of the debate, according to Green Party officials. The Oct. 3 debate includes Republican candidate George W. Bush and Democratic candidate Al Gore.

Nader should be allowed to participate in the televised face-off, said Green Party organizer Annette Ramos, who expects about 13,000 people to attend the rally.

On Thursday, the Bush and Gore campaigns announced they would agree to three nationally televised debates and one vice-presidential debate before the Nov. 7 election.

Bush had initially balked at the proposal of the bipartisan Commission on Presidential Debates, which called for the three national debates.

The commission has said that only candidates with the support of at least 15 percent of the electorate in media polls would be allowed into the debates.

Nader and Reform Party nominee Pat Buchanan have both registered in the single digits in national polls and likely will be barred from the debates.

Nader had filed a federal lawsuit claiming corporate sponsorship of presidential debates is illegal because it amounts to corporate contributions to political campaigns, which are barred by law.

This year, AT&T, Anheuser-Busch and Sun Microsystems, are among companies making tax-deductible contributions to the nonprofit Commission on Presidential Debates.

U.S. District Court Judge Patti Saris ruled the debates are nonpartisan, and encourage people to vote, and thus meet an exception to federal rules prohibiting corporate contributions in federal elections.