mel martinez

GOP Sen. Mel Martinez Is Resigning.

Sen. Mel Martinez, who announced last year that he wouldn't seek re-election in 2010, told his staffers at a meeting Friday morning that will not return to the Senate after the August recess.

Sen. Mel Martinez, R-Fla., is resigning, a senior Republican official told FOX News.

Martinez, who announced last year that he wouldn't seek re-election in 2010, told his staffers at a meeting Friday morning that will not return to the Senate after the August recess. "My priorities have always been my faith, my family and my country and at this stage in my life, and after nearly 12 years of public service in Florida and Washington, it's time I return to Florida and my family," Martinez said in a written statement.

"So today I'm announcing my decision to step down from public office, effective on a successor taking office to fill out the remainder of my term."Martinez will make a formal announcement at a news conference planned for Friday at 3 p.m. in Orlando.Several sources told FOX News that Martinez wants to return to Florida to help resolve some family issues.Rumors had been swirling for months that Martinez would resign early.His resignation will allow Gov. Charlie Crist, who is running for the seat, to appoint a replacement. Sources told FOX News that Crist will appoint a placeholder and let the primary unfold as usual. But Crist is not likely to appoint himself because it could alienate voters.

It is unclear whether Martinez would endorse a candidate.

With Democrats holding a commanding 60-seat majority in the Senate, every seat is critical for Republicans. The Florida race has captured national attention because it is one of several contests in which the GOP must find strong candidates to run.Martinez announced in December that he would not seek a second term in 2010, also citing a desire to spend more time with his family.He denied that he faced difficult re-election prospects in a state won by President Obama. But he has struggled to boost public support because of his close ties to President George W. Bush and his efforts pushing an immigration bill that was unpopular with many Republicans.Martinez was elected in 2004 after serving as the U.S. secretary of housing and urban development during the Bush administration. He served as general chairman of the Republican National Committee for 10 months, resigning in October 2007.

FOX News' Major Garrett and Trish Turner and The Associated Press contributed to this report.