WASHINGTON -- Al Gore's campaign chairman tried Tuesday to increase pressure on rival George W. Bush to accept three nationally televised, prime-time debates, saying they would "give the greatest number of voters the chance to hear the candidates directly."

In a letter to the Commission on Presidential Debates, Gore campaign chairman William Daley formally endorsed the commission's proposal for presidential forums on Oct. 3 in Boston, Oct. 11 in Winston-Salem, N.C., and Oct. 17 in St. Louis which would be available for broadcast by all TV networks.

Bush responded, "I would welcome all three being in prime time." But his campaign said that didn't necessarily mean he would accept any of the commission's proposed dates or formats.

The Republican made clear that he prefers relatively informal debates, such as the session during the Republican primaries in which the participants were seated around a table with CNN talk show host Larry King.

Daley, Gore's campaign manager, said in his letter that the debate commission's proposal would offer "the best opportunity for the most Americans to see the presidential candidates in the most effective forum to debate their views."

Bush has agreed to three presidential debates without specifying which ones. Democrat Gore, who has accepted dozens of debate invitations, has accused Bush of shopping around for a format that few people would watch, such as a cable or Sunday morning talk show.

In the meantime, Bush's campaign manager, Joe Allbaugh, has met with commission co-chairman Frank Fahrenkopf Jr., himself a former GOP national chairman, a Bush spokesman said.

The Bush campaign had thought the commission's format was not negotiable, but in the meeting with Fahrenkopf, "there seemed to be some indication that the commission was willing to be a little bit more flexible," said Bush Communications Director Karen Hughes.

Bush has also proposed two vice presidential debates, instead of the commission's recommended lone face-off between Democrat Joseph Lieberman and Republican Dick Cheney.

Daley endorsed that proposal and encouraged the commission to schedule an additional forum for the running mates.