Sen. Mel Martinez (Fla.) stepped down as general chairman of the Republican National Committee today, ending a nine-month stint at the top of a party marred by ugly intra-party fights over immigration and a continuous struggle by Republicans to redefine themselves in the post-Bush era.

In an RNC statement announcing his resignation, Martinez said he is stepping down now that the party is in a position to provide support for their next presidential nominee, which had been his goal going into the job.

“It was my goal as General Chairman to lead the Party as it established the structure and raised the resources necessary to support our Presidential candidate and ensure Republican victories next November. I believe we have accomplished those goals. That’s why it is the appropriate time for me to step down as General Chairman and continue to focus my energy on serving my constituents in Florida,” Martinez said in the statement.

Senate Minority Leader Mitch McConnell (R-Ky.) praised Martinez in a statement released Friday. “Mel has served as an effective voice for our party, and we appreciate his success in communicating the Republican agenda of strong national and economic security. He is a respected member of our conference and will continue to play an important role in the Senate and through his continued service to the people of Florida.”

Likewise, President Bush, who appointed Martinez to the slot, thanked the Floridian’s work as general chairman. “As General Chairman of the Republican National Committee, Mel has effectively communicated our party’s commitment to addressing the issues most important to all Americans. … As his tenure at the RNC ends, Mel should be proud that he has represented the best of the Republican Party and its core values. I am grateful for his leadership at the RNC, his service in my Cabinet, and his continued service as a member of the United States Senate,” Bush said in a statement.

But privately, for months Republicans have complained that Martinez has shown little interest in the job. GOP insiders also have argued that his close relationship to Bush — whose poll numbers have collapsed over the past 12 months — has hampered Republicans’ efforts to begin transitioning into the post-Bush era.

For instance, these sources point out that Bush had hoped that Martinez’s being Hispanic would help the GOP woo Latino voters. But his involvement in this spring’s disastrous immigration fight, which splintered Republicans, largely alienated him from much of the party’s conservative base, while many Hispanics became increasingly leery of what many of them viewed as an anti-immigrant wing of the GOP.

The RNC filed its October monthly report Friday, showing that the committee had raised $5.8 million in September and had $16.5 million in the bank at the end of the month.