WASHINGTON (CNN) -- Sen. Mel Martinez, a Florida Republican, announced Friday that he will resign his seat as soon as a replacement can be named by the governor.
Sen. Mel Martinez is the only Hispanic Republican in the U.S. Senate.
"My priorities have always been my faith, my family and my country, and, at this stage of my life and after nearly 12 years of public service in Florida and in Washington, it is time to return to Florida and my family," the 62-year-old said in Orlando, Florida.
"So today I am announcing my decision to step down from public office."
Martinez said he is resigning "of my own free will. There is no impending reason; it's only my desire to move on and to get on with the rest of my life."
He added that he is in good health and that he expects the next phase of his life will take place in the private sector.
"However, I do hope that I can have a voice to speak out on issues I think are important," he said.
Martinez added that he has no plans to run for any other public office.
At a news conference at McDill Air Force Base in Florida, Gov. Charlie Crist said he will "undertake a very thorough, comprehensive, thoughtful process" to find a replacement for Martinez.
He vowed not to appoint himself to complete Martinez's six-year term, which ends in about 17 months, and predicted that he would reach a decision before the Senate returns from recess September 8.
Crist, a Republican, had announced in May that he would not seek a second term as governor and instead would run for Martinez's seat in the 2010 election.
Martinez was elected in 2004. He announced in December his intention to retire at the end of his term.
Martinez is the only Hispanic Republican in the Senate. He joined eight other Republicans on Thursday in voting to confirm Judge Sonia Sotomayor as the first Hispanic justice to serve on the U.S. Supreme Court.
Democrats hold a tenuous filibuster-proof majority in the Senate, with 60 votes. Martinez is one of six Republicans who have stated they would not seek re-election in 2010. But the Florida senator is the second Republican who has decided to leave before the curtain drops on the 111th Congress next fall.
Sen. Kay Bailey Hutchison, R-Texas, recently announced her intention to quit the Senate three years before her term expires, in order to run for governor next year.
The five other Republicans who are retiring are Missouri Sen. Kit Bond, Kansas Sen. Sam Brownback, New Hampshire Sen. Judd Gregg, Kentucky Sen. Jim Bunning and Ohio Sen. George Voinovich.
Two Democrats will not run in 2010: Illinois Sen. Roland Burris and Delaware Sen. Ted Kaufman.
Republicans must defend 19 seats next year, and Democrats must protect 18.
CNN's Rick DiBella, Mark Preston and Deirdre Walsh contributed to this report.