PASCAGOULA, Miss. Nov. 26 — Senator Trent Lott of Mississippi, who was forced to step down as Republican leader in 2002 after making a remark that seemed to support segregation, announced today that he will resign by the end of the year.

Speaking to a crowd of supporters at a televised news conference in Pascagoula, Miss., Mr. Lott said he and his wife, Trish, had decided that they still had enough “time left to do something else” after his 35 years in the House and Senate.

He said he had “nothing definite at this time,” but suggested he might want to teach. He said he had called President Bush and Vice President Cheney last night to notify them of his decision.

He was re-elected in 2006 to his fourth Senate term and had rebounded to become the No. 2 Republican this year after his party had lost its majority in the Senate. But in recent months, Mr. Lott, 66, has made no secret of his deepening frustration in the Senate, not only because his party is in the minority but also because an increasingly bitter partisan divide this year has left little use for his skills as a deal-maker.