Updated: 12:50 p.m.

After throwing his hat into the Sunshine State’s Senate race Tuesday morning, Florida Gov. Charlie Crist became the instant frontrunner for his party’s nomination and earned swift endorsements from GOP leaders on Capitol Hill.

“I am pleased to endorse Governor Charlie Crist and provide my full support for his candidacy for the United States Senate,— Senate Minority Leader Mitch McConnell (R-Ky.) said in a statement Tuesday morning. “Decisions are being made every day in Washington that have a direct impact upon the lives of all Americans and we need Charlie Crist in the U.S. Senate to ensure that those decisions will benefit the citizens of Florida.—

Meanwhile National Republican Senatorial Committee Chairman John Cornyn (Texas) pledged the committee would support Crist’s campaign.

“Governor Crist is a dedicated public servant and a dynamic leader, and the National Republican Senatorial Committee will provide our full support to ensure that he is elected the next United States Senator from Florida,— he said.

But before he can claim the GOP nomination, Crist will have to defeat former state Speaker Marco Rubio, who announced his Senate plans last week.

In the wake of Sen. Mel Martinez’s (R-Fla.) retirement announcement, the NRSC met with Crist and Rubio, and party officials had talked up both candidates in recent months.

Cornyn took time to praise Rubio but said Crist represents the party’s best chance of holding the seat in 2010.

“While I believe Marco Rubio has a very bright future within the Republican Party, Charlie Crist is the best candidate in 2010 to ensure that we maintain the checks and balances that Floridians deserve in the United States Senate,— Cornyn said.

Rubio, who has earned some notable early encouragement from the Club for Growth, released a statement Tuesday morning welcoming Crist to the race.

“Our primary will offer Republicans a front row seat to a debate about the future of the Republican Party here in Florida and across the nation,— Rubio said in his statement. “My campaign will offer GOP voters a clear alternative to the direction some want to take our party.—

To emphasize that point, Rubio released a new ad on his campaign Web site and YouTube.com this morning, tying Crist to President Barack Obama.

“Some politicians support trillions in reckless spending, borrowed money from China and the Middle East, mountains of debt for our children, and a terrible threat to a fragile economy,— an announcer in the ad states over a visual of Crist and Obama together. “Today too many politicians embrace Washington’s same old broken ways but this time there is a leader who won’t. Let the debate begin.—

Meanwhile the Democratic Senatorial Campaign Committee also took a shot at Crist following his announcement.

“Charlie Crist’s record in Florida is not one to be proud of,— DSCC spokesman Eric Schultz said in a release. “Too many in Florida are hurting because Governor Crist has failed to provide leadership and a way out of this mess. He’s jumping ship when he’s needed the most. That isn’t leadership — it is an abdication of responsibility.—