Senator Robert Menendez of New Jersey, a Democrat, was charged in September with accepting bribes, including cash, gold bars and a luxury Mercedes-Benz, in exchange for lucrative political favors and what prosecutors described as efforts to derail criminal investigations.

Federal prosecutors in Manhattan have twice expanded the accusations by filing revised indictments.

In October Mr. Menendez, 70, was additionally charged with conspiring to act as an agent of Egypt while also serving as chairman of the Senate Foreign Relations Committee. And on Tuesday, prosecutors said he had used his power to aid the government of Qatar, a tiny Gulf state and major natural gas exporter that hosted the World Cup in 2022.

Three New Jersey businessmen and Mr. Menendez’s wife, Nadine Menendez, are also charged in the bribery scheme. All have pleaded not guilty, and their trial is scheduled to start in May in Manhattan.

The senator has strenuously denied the charges and has refused widespread calls from fellow Democrats to resign.