TALLAHASSEE, FLA. ? A month after dropping out of the White House race, Sen. Bob Graham announced Monday he will retire when his term is up next year, dealing a blow to the Democrats’ bid to take back the Senate.

Democrats had high hopes that Graham, one of Florida’s most popular politicians, would win a fourth term in 2004. But in the end, Graham said he had to make the decision that was best for him and his family, including his wife, four daughters and 10 grandchildren.

“This has been a very difficult decision for me and my family and I know for some of you it is a disappointment,” Graham, who turns 67 on Sunday, said at a high school where he was conducting one of his “workdays” as a roofer.

Republicans hold a 51-48 majority in the Senate, with one Democratic-leaning independent. Three other Senate Democrats — all Southerners — have also announced plans to retire: Zell Miller of Georgia, John Edwards of North Carolina and Ernest “Fritz” Hollings of South Carolina.

Graham’s decision is “a tremendous setback” to Democratic chances in the Senate next year, said Larry Sabato, a University of Virginia political science professor and close observer of Southern politics. “The odds already were that the Republicans not only would retain control but would add seats in the Senate.”

Graham said the Democrats still had a chance of recapturing the Senate. He said he had taken the party’s prospects into consideration in making his decision.

Graham’s announcement marks an end to a storied political career that spans more than 35 years. After serving in the Florida Legislature from 1966 to 1978, Graham was elected to two terms as governor and then moved on to the Senate in 1987. Graham has never lost a statewide election.

As leader of the Senate Intelligence Committee, Graham has been at the forefront of the debate over the nation’s preparedness against terrorism since Sept. 11.

Graham based much of his presidential campaign on his vote against the war in Iraq. Yet anti-war activists preferred former Vermont Gov. Howard Dean’s fist-pounding indignation to Graham’s calm, measured arguments against President Bush’s foreign policy.

Perhaps his best known gimmick is the monthly “workday” he established as governor: He spends the day at an ordinary job, such as bagging groceries or serving airline passengers as a flight attendant. He announced his retirement on his 391st workday.

Sen. Bob Graham, D-Fla., waves to the media as he reaches the roof of a local high school in Tallahassee, Fla. Graham was working with a local construction company roofing the building. Later Monday, Graham announced that he would not seek re-election to a fourth term in the U.S. Senate.