Updated May 12, 10:50 a.m.

With Florida Gov. Charlie Crist (R) set to jump into the open-seat Senate race today, a cascade of dominoes are expected to begin falling across the Sunshine State as federal and state candidates begin to reshuffle their 2010 electoral plans.

Among those who have been waiting on an announcement from Crist is sophomore Rep. Vern Buchanan (R). After openly expressing his interest in the Senate race if Crist were to pass, Buchanan has more recently acknowledged that he has been encouraged to run a gubernatorial race in an open-seat scenario.

However, Buchanan announced Tuesday morning that he would not run for governor and would seek re-election instead. “Representing Florida’s 13th district in the U.S. House is an honor and a privilege,— Buchanan said in a statement. “I look forward to the opportunity to continue serving the people.—

Had he decided to give up his seat in Congress for a shot at the governor’s mansion, Buchanan’s departure would have likely set up a competitive open-seat battle in his Sarasota-based district.

Possible Republican candidates include state Sens. Mike Bennett and Nancy Detert, who lost the 2006 open-seat primary to Buchanan by about 5,000 votes. Also being mentioned are state Rep. Bill Galvano, businessman Henry Rodriguez and Tramm Hudson, who came in third in the 2006 GOP primary.

A spokeswoman for the National Republican Congressional Committee said the party is confident it will hold the seat even if Buchanan leaves.

“Republicans perform well in this district, thanks to great candidates like Vern Buchanan,— Joanna Burgos said. “If the seat ends up being open, we’ve got a deep bench of strong Republicans in the district.—

Buchanan’s first election in the 13th district — part of the state’s fast-growing Interstate 4 corridor — came down to just 369 votes. The wealthy former auto dealer handily beat Democrat Christine Jennings in a rematch last cycle, but President Barack Obama held Sen. John McCain (R-Ariz.) to just 52 percent of the vote in the presidential race in the 13th.

National Democrats are pushing state Rep. Keith Fitzgerald as a top contender if the seat becomes open. The two-term state legislator, who is also a professor at a small liberal arts college, said he would seriously consider running in an open-seat race but would probably pass if Buchanan stays put.

The district “is trending in a much more moderate direction than it used to be,— Fitzgerald said. “When this was gerrymandered eight years ago, [Republicans] did a very good job. … But times have changed.—

Democrats insist the district has the potential to be competitive with or without Buchanan in the race.

“Floridians in the 13th Congressional district who have been hit hard by this economy and the homeowners insurance crisis will be looking for a Representative who offers real solutions, instead of just saying no,— Democratic Congressional Campaign Committee spokeswoman Jessica Santillo said on Monday.

But Fitzgerald acknowledged that Buchanan would not be an easy target to defeat.

“Anytime somebody gets past their first re-election, the odds of knocking them off are very difficult. … The seat has moved more toward the center … but [Buchanan] has followed that trend.—

Buchanan spokeswoman Sally Tibbetts declined to discuss Buchanan’s 2010 plans on Monday, noting that the Congressman would make his decision after Crist’s announcement. But Florida GOP insiders said they wouldn’t be surprised either way if Buchanan jumps in or passes on a gubernatorial bid.

The Congressman’s deep pockets and ambition for higher office are well-known — he ended March with a half-million dollars in his re-election account — but Florida’s GOP gubernatorial primary is also expected to be a free-for-all that will likely feature powerful players such as Attorney General Bill McCollum who, according to recent polling, has strong approval numbers. It wouldn’t be an easy path, and Buchanan’s GOP rivals would certainly focus on his more moderate Congressional voting record in the primary.

Meanwhile, well-known and well-liked state Chief Financial Officer Alex Sink, whom national Democrats tried to woo into the Senate race, will likely be waiting in the general election.