(NEW YORK) -- Federal prosecutors filed new charges Thursday against Sen. Bob Menendez, D-N.J., accusing him of violating a prohibition on members of Congress from acting as an agent of a foreign principal.
The superseding indictment said Menendez "made multiple requests for the U.S. Department of Justice to commence an investigation against another person for allegedly failing to register under FARA."
Menendez faced a sweeping indictment in late September accusing him and his wife of accepting hundreds of thousands of dollars of bribes in exchange for using the senator's power and influence to seek to protect and enrich the businessman.
The superseding indictment includes four new charges and appears to mark the first time a sitting member of Congress has ever been charged with conspiracy for a public official to act as a foreign agent.
The indictment alleges Menendez conspired with his wife, Nadine Menendez, and New Jersey businessman Wael Hana to have the senator act as an agent of Egypt.
The indictment includes new photos of Menendez, his wife and Hana dining with Egyptian officials that prosecutors said were part of a "corrupt agreement" to provide the senator and his wife with hundreds of thousands of dollars in bribes in exchange for official acts taken to benefit the Egyptians.
Once Nadine Menendez informed her friend Hana that she was dating Menendez, prosecutors said the two "arranged a series of meetings and dinners" with Egyptian officials. In exchange for bribe payments, Menendez was meant to help lift a block on U.S. military aide to Egypt, the indictment says.
The new indictment also alleges Nadine Menendez set up an LLC to receive bribe payments, quoting a message from her saying "every time I'm in a middle person for a deal I am asking to get paid and this is my consulting company."
As part of the new charges, federal prosecutors sought to seize the senator's home in Englewood Cliffs, New Jersey, the 2019 Mercedes convertible prosecutors said Nadine Menendez bought with bribe money, nearly half a million dollars in cash and multiple gold bars.
Reached by phone, the senator's defense attorney, David Kolansky, said he had no immediate comment.
The superseding indictment says Menendez "made multiple requests for the U.S. Department of Justice to commence an investigation against another person for allegedly failing to register under FARA," who appears to be former Republican congressman David Rivera from Florida, who Menendez accused of being an agent for Venezuela's Nicolas Maduro.
Menendez, as well as his wife, pleaded not guilty to the first set of charges on Sept. 27.
Sen. Marco Rubio, the No. 2 member on the Senate Intelligence Committee behind Menendez, told reporters just after the news broke that he had not yet seen the reporting, but called it concerning.
"Yeah, I mean, who's in favor of that? I mean, of course it's concerning," Rubio said, but added that Menendez has a right to defend himself.
"I'm hearing it from you for the first time so if he wants to defend his record, he has a right to do so. And in our country, the government is tasked with the job of proving those cases," Rubio told reporters.
Menendez has said he will not step down and strongly denounced the charges in a press conference.
"Everything I've accomplished I've worked for despite the naysayers and everyone who has underestimated me," he said on Sept. 25. "I recognize this will be the biggest fight yet. But as I have stated throughout this whole process, I firmly believe that when all the facts are presented, not only will I be exonerated, but I still will be New Jersey's senior senator."
ABC News' Elizabeth Landers contributed to this report.