Florida Gov. Charlie Crist announced Tuesday that he'll skip a second term as the state's chief executive and run for the U.S. Senate seat being vacated by fellow Republican Mel Martinez next year.
Crist, 52, has maintained approval ratings in the high 60s despite the state's gloomy economy, budget cuts, a high foreclosure rate and the highest unemployment since 1975.
The moderate Republican faces a primary challenge from former Florida House speaker Marco Rubio, a conservative who is questioning Crist's commitment to Republican principles.
"The challenges that Florida faces are not just Florida challenges, they're national issues," Crist said. "I believe I can best serve the people of Florida — if they're willing to allow me — as their next United States senator."
Crist drew immediate support from the national party establishment, including Sen. John Cornyn of Texas, head of the Senate GOP campaign committee, and Senate Minority Leader Mitch McConnell of Kentucky.
"Gov. Crist's support appears to be both wide and deep," said Peter Brown, assistant director of the Quinnipiac Polling Institute. "As for a primary, although some conservative activists have grown disillusioned with him, there is no evidence that unhappiness has spread to the GOP rank-and-file."
Rubio, 37, a Miami lawyer and son of Cuban immigrants, posted a YouTube video showing Crist welcoming President Obama to Florida.
The image in the video is from an appearance Crist made with Obama to promote the $787 billion federal stimulus package, which was opposed by all congressional Republicans except three.
"Borrowed money from China and the Middle East, mountains of debt for our children and a terrible threat to a fragile economy. Today, too many politicians embrace Washington's same old broken ways," an announcer says on the Rubio video. "Let the debate begin."
In an interview on Fox News Channel, Rubio said his party needs to "choose what we want 'Republican' to mean." He said he likes Crist but "his view of Republicanism is different than mine."
Last year, Crist was a vocal supporter of Republican John McCain and a frequent spokesman for his party's presidential nominee.
The governor has been an atypical Republican in other ways. Crist refused to get involved in the Terri Schiavo right-to-die case when he served as attorney general. During the governor's race in 2006, he took a "live and let live" attitude on same-sex civil unions and said he wants to change hearts and not abortion laws.
Since taking office, he has championed some issues important to Democrats, including banning touch-screen voting machines, helping felons get their voting rights back and pushing for tough clean-energy standards for electric plants.
In 1998, Crist left the state Senate to seek the same U.S. Senate seat, losing to Democratic incumbent Bob Graham. That race helped Crist build his name recognition and a network that helped him win the next three statewide races he entered: education commissioner in 2000, attorney general in 2002 and governor in 2006.
Democrats will target Crist as they try to maintain what could be a 60-vote majority in the Senate, the number they need to overcome GOP filibusters and help pass Obama's legislative agenda. Democrats would likely control 60 votes if Al Franken, who is leading after a recount, is declared the winner in the Minnesota Senate race.
"My fear is that the governor's Senate candidacy is not going to be as smooth and effortless as it seems at this point," said Roger Stone, a Republican political consultant.
The Democratic Senatorial Campaign Committee, which had already been running a TV ad against Crist in Tallahassee, quickly pointed out Florida's economic problems and budget cuts.
"Too many in Florida are hurting because Gov. Crist has failed to provide leadership and a way out of this mess. He's jumping ship when he's needed the most," committee spokesman Eric Schultz said.
Florida Democrats running for Senate include U.S. Rep. Kendrick Meek and state Sen. Dan Gelber, both from Miami-Dade County.
Contributing: Bill Cotterell, Gannett Tallahassee bureau; the Associated Press