Senator Mel Martinez, the Florida Republican who has served as general chairman of the Republican National Committee, stepped down yesterday after 10 months on the job.

In a statement, Mr. Martinez said he had met his goals of raising “the resources necessary to support our presidential candidate and ensure Republican victories next November.”

He served alongside Robert M. Duncan, who is chairman of the party and will remain so.

The Republican National Committee has a six-to-one advantage over the Democratic National Committee in cash on hand. But Democrats point out that Mr. Martinez raised less in his tenure from January to July of this year ($52 million) than his party raised in the same period four years ago ($68 million).

Republicans close to Mr. Martinez said that he was increasingly uncomfortable as the face of the party.