A first-of-its-kind summit in Florida has secured commitments from more than four Republican presidential contenders as the state GOP seeks to build up its ranks ahead of next year's general election.

The Republican Party of Florida announced on Tuesday that former Florida Gov. Jeb Bush, Sens. Marco Rubio (R-Fla.) and Lindsey Graham (R-S.C.) and Louisiana Gov. Bobby Jindal plan to attend the inaugural Sunshine Summit, to be held Nov. 12-14 in Orlando. Other candidates are expected to confirm their attendance by the end of the week, according to state party officials. This is the first time the state party has hosted such a cattle call, an event that Republicans hope will boost interest in the campaign ahead of the March 15 primary and next year's general election.

March 15 is the first day that primaries become winner-take-all contests. With the Ohio, Illinois and Missouri Republican primaries also scheduled that day, it could be a night that settles the nomination fight or significantly winnows the field.

"The road to the White House goes through Florida, and our State Party is taking on the mission of strategically and tactically fighting for every vote across our state to ensure that we elect a Republican as the next president of the United States," Florida GOP Chairman Blaise Ingoglia said in a statement announcing the initial lineup.

Other candidates are expected to confirm plans to attend in the coming days, according to party officials.

The announcement also comes a week after Florida Republicans set first-of-its-kind rules to appear on the primary ballot. Presidential contenders can opt to do one of three things: Attend the summit; pay a $25,000 entrance fee; or obtain the signatures of 3,375 registered Florida Republicans, with at least 125 coming from each of the state's 27 congressional districts.

Bush and Rubio's decision to attend is no surprise, especially because the state is so critical to their chances. But Graham and Jindal's decision to show up signals that presidential candidates aren't going to cede the state to Florida's favorite sons.

One name not on the initial list of speakers: Donald Trump, who has topped recent Florida polls. He placed first in a Jacksonville University poll and another by Florida Atlantic University. Bush placed second in the JU poll, while Rubio placed second behind Trump in the FAU survey.