Sen. Mel Martinez (R-Fla.) announced his imminent resignation in a letter to supporters Friday, nearly a year and a half before his term is due to expire in January 2011.
Martinez is expected to announce his decision formally at a 3 p.m. press conference in Orlando.
Crist is running for Martinez’s seat and could appoint himself as a replacement, said a spokeswoman for the Florida Secretary of State. The state’s only restriction is that Crist could not serve as governor and senator simultaneously.
Martinez was rumored earlier this year to be contemplating a resignation before the end of his first term but Martinez denied it.
Friday’s surprise resignation prompted head scratching among Republicans on the Hill.
One GOP aide speculated that Martinez, the Senate’s only Hispanic Republican, resigned because of differences with his party over immigration.
Martinez pushed unsuccessfully for immigration reform that would have created a path to citizenship for the nation’s estimated 12 million illegal residents. But the legislation failed in the face of staunch opposition from the party’s base.
One of his last acts as a senator was to vote to confirm Sonia Sotomayor as the first Hispanic justice of the Supreme Court. Only eight other Republicans voted for her.
In his letter to supporters, Martinez gave little clue to his reasoning, stating only: “After nearly twelve years of public service in Florida and Washington, it’s time that I return to Florida and my family.”
Crist is expected to appoint a caretaker to hold the seat until next year’s election. The governor raised more than $4.3 million in his first seven weeks as a candidate. He is facing a primary race against former Florida state House Speaker Marco RubioMarco RubioRepublicans play clean up on Trump's foreign policy Top Dem: GOP is terrified of Trump McConnell on Trump: 'I'm not a fan of the daily tweets' MORE. Rubio raised only $340,000 in the second quarter of 2009.
“My initial reaction that this was set up for Crist to appoint himself,” said Jason Roe, a political consultant who served as chief of staff to former Rep. Tom Feeney (R-Fla.). “But there’s a high potential of backlash if that is the case.
“If I were Charlie Crist right now and trying to decide how to react to this, I would put in a placeholder senator and continue to campaign to be elected legitimately.”
Other Republicans expressed similar sentiments.
On the Democratic side, Rep. Kendrick Meek (D-Fla.) is considered the early frontrunner for Martinez’s seat. He faces a potential challenge from Rep. Corrine BrownCorrine BrownDemocrats offer double-talk on Veterans Affairs House Democrats have opportunity for redemption in selecting VA Cmte Leader Women make little gains in new Congress MORE (D-Fla.), who has formed an exploratory committee.
This story was updated at 1:15 p.m.