Al Gore left the field of potential 2004 Democratic presidential candidates in a surprise move that immediately raised the stakes for a half-dozen others pondering a run for the White House. Sen. Joseph Lieberman said Monday he'll announce early next month whether he plans to run.

Gore made his announcement Sunday on CBS "60 Minutes," taking the nation and party faithful by surprise. Some close aides had expected him to start making calls to political and financial advisers to test the waters and then make a decision over the Christmas holidays.

While saying he still had the energy and drive to run again, Gore, 54, noted "there are a lot of people within the Democratic Party who felt exhausted (by the 2000 race) ... who felt like, OK, `I don't want to go through that again.' And I'm frankly sensitive to that feeling."

President Bush's spokesman called the developments an internal Democratic Party matter, but couldn't resist taking a poke. "Someone will emerge from the Democratic pack who seeks to raise taxes on the American people. ..." White House press secretary Ari Fleischer said.

After seeking the presidency or vice presidency every four years since 1988, Gore said Sunday he'll probably not have another chance to run for the White House.

And he said a rematch with President Bush "would inevitably involve a focus on the past that would in some measure distract from the focus on the future that I think all campaigns have to be about."