Following Sen. Mel Martinez’s (R-Fla.) surprise announcement he will not seek a second term in 2010, a long line of potential would-be successors had already begun to form by Tuesday afternoon.

Rep. Allen Boyd (D) became one of the first to officially say he is thinking about running for the open seat, in what is likely to be a contest that draws a crowded field of candidates from both parties. Boyd, who considered running for Senate in 2004, said he expects to make a final decision by early next year.

“I have been considering a run for the U.S. Senate in 2010, prior to Sen. Martinez’s announcement today,” Boyd said in a statement. “I will continue to discuss the race with state and national party leaders and with my supporters in North Florida and throughout the state.”

Besides Boyd, several Democratic House Members were also mentioned as possible contenders for the open Senate spot by state Democratic insiders on Tuesday. Foremost among them were Rep. Ron Klein (D), who is currently carrying a nearly $2 million campaign war chest, and Rep. Kendrick Meek (D), a rising star in the House known for his battles with former Gov. Jeb Bush (R) over education and affirmative action when he served in the Florida Legislature.

A Klein spokeswoman said the Congressman remains focused on his current work in the House but did not address his possible interest in a Senate bid.

Freshman Rep. Kathy Castor (D), whose mother lost a Senate bid to Martinez by just 1 point in 2004, could also be in the mix. Another outside possibility could be Rep. Debbie Wasserman Schultz (D), but considering how quickly the 2nd term Congresswoman is rising in House leadership circles, a Senate bid may be less likely at this time.

Outside of Florida’s House delegation, state Sen. Dan Gelber’s (D) name has been mentioned as a possible candidate for the Senate seat.

Still, most all Democratic eyes in the Sunshine State remain focused on the state’s chief financial officer, Alex Sink.

Elected in 2006, the former Bank of America executive was the first Florida Democrat to be elected to nonfederal statewide office since 1992, and she has long been considered a likely 2010 gubernatorial or Senate candidate. But despite that speculation, reports earlier this week indicated that Sink was planning on seeking re-election to her CFO post in 2010.

But the Martinez news may have changed all that as Sink canceled a press conference that was slated for Tuesday afternoon.

Sink’s strengths come in the form of her moderate profile, financial background and a Southern accent that plays well in Florida. While the only elected statewide Democrat is widely viewed as the party’s strongest candidate in the race, the Democratic Senatorial Campaign Committee declined to comment Tuesday afternoon on any possible efforts to woo Sink into the open-seat contest.

“We never comment on our conversations with candidates or potential candidates,” DSCC spokesman Matt Miller said. “That seat was one of the top battleground seats before Martinez retired, and it will continue to be a battleground seat. It is a huge opportunity for a Democratic pickup.”

On the Republican side, Bush and current Florida Gov. Charlie Crist rise to the top of any potential candidate list. If either man decided to throw his hat into the ring, they would be considered “game changers” in a Republican primary, said David Johnson, the former executive director of the Florida Republican Party and a Tallahassee-based GOP consultant.

“Those would be the only two with the financial and political power to clear a primary field,” Johnson said.

Rep. Adam Putnam, who is stepping down from his position as House GOP Conference chairman and is viewed as having statewide ambitions, is among the Republicans in the House delegation who will likely consider making a Senate run.

Two-term Rep. Connie Mack IV (R), whose father served in the Senate from 1989 until 2001, is also mentioned as a possible candidate.

In the state Legislature, Florida House Majority Leader Adam Hasner (R) and former state Speaker Marco Rubio (R) could jump into the Senate race along with state Senate President Jeff Atwater. Meanwhile Florida Attorney General Bill McCollum (R), who lost the Senate primary to Martinez in 2004, could also take another shot at the seat.

News of Martinez’s retirement broke suddenly on Capitol Hill Tuesday morning taking most lawmakers by surprise, including Sen. John Cornyn (Texas), the incoming chairman of the National Republican Senatorial Committee.

Republican sources said Martinez did not give Cornyn advance warning of his decision, which he announced at an 11 a.m. news conference in Orlando. However, the two Senators did speak before Thanksgiving, and Martinez hinted to the incoming NRSC chairman he might forgo a second term in order to spend more time with his family.

Martinez stepped down as the Republican National Committee co-chairman last year, saying he wanted to focus on home state politics. At the time, most predicted he wanted to step away from a highly partisan position in order to secure his footing for 2010.

In a statement released by Cornyn’s office Tuesday afternoon, the Texas Senator praised Martinez’s record of public service, but did not address the looming project before him: protecting an open seat in a state that is competitive and expensive.

Although the 2010 Senate map is stacked against Republicans, Cornyn dodged one bullet recently when Sen. John McCain (R-Ariz.) revealed he would run for re-election despite losing his bid for the presidency.

“The story of Sen. Mel Martinez is the story of the American dream,” Cornyn said. “He has achieved an extraordinary level of success through pure hard work, dedication and determination.”

Martinez said in remarks released by his office that his decision had nothing to do with the prospect that he might face a tough re-election fight, and everything to do with his desire to spend more time with his family and friends. The Floridian said he was making his decision early in order to give those who might succeed him enough time to put together a winning campaign.

“My decision was not based on re-election prospects, but on what I want to do with the next eight years of my life,” Martinez said. “The thought of devoting more time to my roles as husband, dad, granddad, brother and son to the family I love and cherish, and to be ‘Mel’ to the friends I miss — makes this decision far easier than one might think.”

David M. Drucker and Shira Toeplitz contributed to this report.