Rep. Jim Davis (D) tossed his hat into the Florida gubernatorial race last week, officially kicking off a contest to succeed him that has been quietly brewing for months.

Hillsborough County Commissioner Kathy Castor and state Sen. Les Miller instantly became the likely Democratic frontrunners to succeed Davis, who has represented the Tampa-based 11th district since 1996.

Once considered a swing seat, it is now a Democratic stronghold, although Republicans say they aren’t willing to write off the open-seat race yet.

Miller, who is expected to make a formal announcement as soon as today, would become the first candidate to officially enter the race.

“We’re 100 percent there,” Miller said Monday. “We’re going to open up a campaign account today.”

Miller said he’s been contemplating a run for Congress since Davis floated the idea of running for governor in 2002. When Davis made his announcement Thursday, Miller decided to move quickly.

“I started making some phone calls and talking to my family and getting everything in place,” Miller said. “It started moving together real fast and we thought it was best to go ahead and start getting everything in place and [announce] as soon as possible.”

He announced last week that doctors have given him a clean bill of health following recent kidney cancer surgery, another factor that expedited his announcement.

Miller, the only black state Senator from the Tampa Bay area, serves as the Democratic leader in the Senate. The 53-year-old state lawmaker also did a stint as Democratic leader in the state House, where he served from 1992 until his election to the state Senate in 2000.

He is a former member of the Tampa City Council and the husband of current Tampa City Councilwoman Gwen Miller.

One of the largest questions surrounding Miller’s candidacy is whether he can raise enough money to remain competitive with Castor, who is expected to have little trouble with resources if she runs.

Castor said Monday that she does not have a timetable for making a decision, but indicated she has significant interest in entering the contest.

“I am very interested,” she said. “It is likely that I will get into that race.”

Castor is the daughter of 2004 Democratic Senate nominee Betty Castor (D), who was narrowly defeated by now-Sen. Mel Martinez (R). Betty Castor, a former state education commissioner, has not ruled out a gubernatorial run next year, a move that could put two Castors on the ballot in the Tampa area.

Kathy Castor argued that the Congressional district mirrors her county commission district demographically and also noted that her mother won more than 60 percent of the vote last year in the 11th.

“There is no question this is a strong Democratic district and it’s one where I’m very familiar with the issues and the people and the activists,” Castor said.

Kathy Castor was elected to the Hillsborough County Commission in 2002. In 2000, she waged an unsuccessful bid for the state Senate.

If Castor runs, she is likely to get the backing of EMILY’s List in the primary. The group, which helps funnel millions to pro-abortion rights Democratic women candidates, heavily supported Betty Castor’s Senate campaign in 2004.

Other potential candidates mentioned are wealthy businessman and former Tampa mayoral candidate Frank Sanchez and child welfare activist and attorney Scott Farrell.

Sanchez, a strong fundraiser, has deep roots in the community and residual name recognition from his loss in the 2003 mayoral race. Sanchez is also well-respected in the heavily black areas of east Tampa.

The district’s black population was increased from 20 percent to 27 percent during the last redraw of Congressional boundaries. Twenty percent of its residents are of Hispanic origin.

Another name that had been mentioned in Davis’ district is state Rep. Bob Henriquez (D), who goes by the nickname “Coach.” But Henriquez, who just took the top coaching job of a local high school football team, appears more likely to run for another opening at this point.

Although Florida state legislators canceled all runoffs in 2004 — establishing winner-take-all primaries instead — a runoff could be forced if no candidate gets more than 50 percent of the vote. The Legislature is expected later this year to decide whether to reinstate runoffs for the 2006 elections.

Davis, a former state House Majority Leader, has easily won re-election ever since coming to Congress in 1996. The 11th district, which includes most of Tampa in Hillsborough County and small portions of St. Petersburg and northern Manatee County, was made much more Democratic during the last round of redistricting. Then-Vice President Al Gore (D) would have received 61 percent of the vote in the redrawn district in the 2000 presidential election. In the old 11th district he got 53 percent.

No Republican names have been mentioned as possible candidates in the 11th district, but National Republican Congressional Committee spokesman Carl Forti said that the party isn’t willing to concede the race just yet.

“We’re going to take a look at any open seat,” Forti said. “The majority, where it is, you can’t just afford to automatically write off open seats. You’ve got to take a look at them.”

Under state law, if a candidate does not have any opposition (including write-in candidates) then his or her name does not even appear on the ballot. In fact, some GOP strategists argue that in some instances it’s better for the party not to field a candidate for fear of driving up Democratic turnout, which could hurt Republican candidates in other races.