WASHINGTON -- Sen. Mel Martinez's decision Friday to cut his term short by 17 months caps a historic though unfulfilled career for the first Cuban-American senator, while handing Gov. Charlie Crist a unique opportunity to choose a temporary successor as he runs for the job himself.

``My priorities have always been my faith, my family and my country and at this stage in my life, and after nearly 12 years of public service in Florida and Washington, it's time I return to Florida and my family,'' the one-term senator told supporters Friday in Orlando after a flight from Washington, D.C., where he told staffers about his sudden, though long-rumored, decision.

Martinez, 62, who said in December that he would not seek reelection in 2010 but repeatedly rejected rumors he would quit early, said, ``There's no impending reason, it's only my desire to move on and get on with the rest of my life.''

Martinez -- who came to the United States from Cuba as a child and often used the Senate floor to deliver impassioned speeches criticizing the regime in Havana -- said he would ``continue that lifelong passion.''

His change of heart jolts an already dynamic political landscape -- with five statewide races, including the open Senate seat, all three Cabinet seats and a race for governor. And it gives Crist -- who must appoint someone to finish Martinez's term -- a chance to put his mark on the seat at a time when the governor himself is the front-runner for the job. Martinez will step down when Crist names a replacement in the next few weeks.

Crist, who enjoys statewide name recognition and has raised $4.3 million for the race, faces a primary challenge from former House Speaker Marco Rubio. Rep. Kendrick Meek of Miami is the leading candidate for the Democratic nomination.

NO SHORT LIST

Crist dismissed speculation that he would step into the Senate seat for the rest of Martinez's term or that he has a short list of replacement candidates.

``I want to assure my fellow Floridians that we will undertake a very thorough, comprehensive thoughtful process,'' he said.

Potential names include former Secretary of State Jim Smith, former Gov. Bob Martinez, former U.S. Rep. Clay Shaw and former U.S. Sen. Connie Mack.

Crist's choice will help define his public image during the 2010 campaign. Under mounting pressure from conservatives, Crist opposed the nomination of Sonia Sotomayor to the U.S. Supreme Court and has softened his support for climate-change initiatives.

Those political pressures could add conservatives such as former lawmakers Dan Webster and Allen Bense to the mix of replacements for Martinez.

``The opportunity to make an appointment like this is so rare, so it says a lot about the person making it,'' said Republican lobbyist Justin Sayfie, who has co-hosted a fundraiser for Crist.

As he offered advice on a placeholder, Rubio delivered a dig at Crist, whom he has criticized for supporting President Barack Obama's $787 billion stimulus package.

``Florida deserves an interim senator who will go to Washington and serve as a true check on President Obama's push for more wasteful government spending, government-run healthcare and cap-and-trade,'' Rubio said.

Also in the mix: Crist's former chief of staff and former deputy attorney general George LeMieux.

Martinez never seemed to relish combative Washington, though he was popular with his colleagues and worked with his fellow Florida senator, Democrat Sen. Bill Nelson, to fend off efforts to put oil rigs near state shores.