Sen. Bob Graham of Florida said Thursday he will undergo heart surgery in early February, postponing any announcement of a bid for the Democratic presidential nomination.

Graham told reporters in his office that he will reassess whether he should run a month after the surgery, which his doctor said should return him quickly to good health.

The 66-year-old Graham said he had tentatively made up his mind to run and was planning to announce his candidacy in Tallahassee Feb. 3, but now will have surgy during medical tests he had conducted to find out if he should proceed with a presidential run.

Graham has been a leading Democratic voice in the war on terror and is the one member of Congress considering a run for the White House who voted against the resolution giving President Bush the authority to use force against Iraq if necessary.

Graham said just before Christmas that he was considering a run for the White House, saying he was "not satisfied with the direction we are being led today."

Graham has been an outspoken critic of White House policy on terrorism and has played a prominent role as a leader of the congressional inquiry into the Sept. 11 terrorist attacks and the failure of the government's intelligence operations.

He was governor of Florida from 1978-1986 and has served in the Senate since then. While Graham has broader experience than most currently considering a run, he would be getting a late start in fund-raising and organizing in early states like Iowa, New Hampshire and South Carolina.

Graham's name has surfaced periodically as a possible candidate in past presidential elections, and he was considered as a vice presidential contender in 2000. Graham's popularity in his native state could be a valuable asset because Florida has 27 electoral votes and is a top source of campaign money for both political parties. Florida has a special significance after its pivotal role in the 2000 presidential election.

Graham has said his opposition to the resolution on using force in Iraq was not intended to play down the threat from Iraq, but a statement about what he feels is an inappropriate shift from the campaign against al-Qaida.

Graham supported the 1991 resolution to use force in Iraq. But he said the resolution approved in October failed to give the president authority to attack Hezbollah and other terror groups and increased the potential for more attacks in the United States.