A congressional aide says Republican Sen. Saxby Chambliss of Georgia won't seek re-election to a third term.
The conservative lawmaker was first elected to the House in the 1994 Republican wave. He moved up to the Senate after a rough 2002 campaign in which he defeated Democratic incumbent Max Cleland, a triple amputee from his Vietnam war service.
The aide spoke on condition of anonymity because he was not allowed to speak in advance of an official announcement.
Chambliss has been a GOP loyalist throughout his career, but he drew criticism from tea party Republicans for his participation in a bipartisan Senate "Gang of Six" focusing on the budget. The group advocated a mix of tax increases and spending cuts but failed to produce a bargain.