I received a tip just now the Mel Martinez has resigned.

Confirmed as reported by Politico.

From Politico:

Sen. Mel Martinez (R-Fla.) will be stepping down from the Senate, according to several senior Republican sources familiar with his thinking.

He made the announcement at a morning staff meeting, where he said he will not be returning to the Senate after the August recess.

Martinez announced he wasn’t seeking re-election to the Senate last December, but he insisted that he would be serving out the remainder of his term, which expires in 2011.

It’s the second time that Martinez has resigned from a high-profile Republican office in the last several years. He stepped down as chairman of the Republican National Committee in October 2007 to focus more on his legislative responsibilities as a senator.

The decision adds a twist to the Florida Senate race. Gov. Charlie Crist (R-Fla.) is the frontrunner for the Republican nomination, and he would be tasked with appointing a candidate to fill the seat until Martinez's term expires in 2011.

National and Florida Republican sources say it's near-certain that Crist will not appoint himself, and instead is expected to appoint a placeholder to fill the seat through the 2010 election.

Taking the seat now and leaving Tallahassee early would risk hurting his solid political standing, Crist allies say, and is unnecessary given his strong positioning to claim the seat next year.

H/T Daniel P.