Republican Party of Florida Chairman David Bitner said Wednesday he would resign because of health concerns, a surprising move that sent the party looking for its fourth leader in less than two years.

"At the time I first discussed my health with you, I also made a promise that I would serve as the Chairman of the Republican Party of Florida only as long as I could do so with all the energy and attention this position deserves," Bitner, who revealed in April that he had been diagnosed with ALS, commonly known as Lou Gehrig's disease, wrote in a letter to Republican activists. "I have kept that promise, and it has been the honor of a lifetime to serve you and my beloved Florida."

Bitner will step aside Sept. 23, amid the party's Presidency 5 event. He recommended that Vice Chairman Lenny Curry, who also heads the Duval County GOP, be elected to replace him.

In his letter to Republicans, Bitner suggested that he had been thinking about the move for some time. He bitterly noted that "some who had been entrusted with my thoughts about the future shared that information with the media."

Republicans praised Bitner for helping stabilize the party after a stormy and tumultuous period leading up to the 2010 elections.

"Because of his leadership and hard work, Florida Republicans are unified and moving forward to ensure Republican victories up and down the ballot in 2012," Republican National Committee Chairman Reince Priebus said. "Daves courage and strength to serve a cause greater than his own while battling a debilitating illness should be an inspiration to us all."

Bitner was elected to head the party in January. He took over for Sen. John Thrasher, R-St. Augustine, who was tapped to head the party in 2010 after financial scandals and support for former Gov. Charlie Crist took down former Chairman Jim Greer who has since been charged with trying to defraud the party. Greer denies the charges.

Gov. Rick Scott lauded Bitner and nodded toward his suggested replacement.

"In his short tenure as Chairman of the Republican Party, Dave Bitner has communicated an inspiring vision for Florida Republicans and he has laid the foundation for a successful 2012 election cycle," Scott said. "I embrace that vision and will do all I can to abide by his wishes and help him carry his vision forward."

In his letter, Bitner said Curry and he had "worked side-by-side on every important RPOF initiative" and urged members to support his No. 2.

"Lenny is more than qualified to continue the work I have begun," Bitner wrote, "and there is no need for the party to face a protracted race or divisive infighting."

House Speaker Dean Cannon, R-Winter Park, and all three members of the Cabinet also backed Curry in statements issued by the party.

Thrasher, who praised Bitner for continuing to stabilize the party, also threw his support behind Curry.

"I think he's an outstanding choice," said Thrasher, whose district includes parts of Duval County. "I think at this point in time we need stability, and I think Lenny can bring stability to the party."

Curry said he didn't plan on a dramatic change in the direction of the party, which faces the task of trying to defeat President Barack Obama in a key swing state; beat incumbent Democratic Sen. Bill Nelson; and working to protect its Congressional and huge legislative majorities in a year when every seat in the Legislature will be up for grabs following redistricting.

"He's got a vision," Curry said of Bitner. "He's got the party on the right path. ... If I am the guy, I'm going to keep following his lead."