The charge comes in addition to a previous indictment alleging Menendez accepted bribes to assist Egyptian interests.
Menendez, 69, and his wife Nadine were previously indicted on federal charges related to allegations they accepted bribes in exchange for using the senator’s official position to benefit the Egyptian government.
But a superseding indictment, filed in a Manhattan federal court on Thursday, raised the stakes further: It added a charge that Menendez conspired to act as “an agent of a foreign principal”.
Menendez has served as a senator from the state of New Jersey since 2006. Until he was charged last month, he also chaired the Senate Committee on Foreign Relations, giving him significant sway over US foreign policy.
He has since stepped down as chair, though he continues to resist calls to resign his elected position.
But corruption allegations have trailed the senator for years, coming to the fore once again with the bribery indictment unsealed on September 22.
US federal prosecutors said that, between 2018 and 2022, Menendez and his wife accepted “hundreds of thousands of dollars’ worth of bribes” from three New Jersey businessmen also charged in the indictment.
Among the alleged bribes were gold bars, a luxury Mercedes-Benz convertible, home mortgage payments and envelopes stuffed with cash, hidden among the clothing in the Menendezes’ closets as well as in a safe.
Both Menendez and his wife have pleaded not guilty to the original indictment. The senator has also sought to frame his actions as the ordinary business of US foreign affairs, rather than nefarious conduct.
“I firmly believe when all the facts are presented, not only will I be exonerated but I will still be the New Jersey senior senator,” Menendez said in a September news conference.
He also argued that his track record on foreign policy towards Egypt contradicted the allegations against him.
“Throughout my 30 years in the House of Representatives and the Senate, I have always worked to hold accountable those countries, including Egypt, for human rights abuses, the repression of its citizenry, civil society and more,” he said.
But prosecutors painted a different portrait of Menendez as someone who entered into a “corrupt agreement” to help Egyptian interests.
They have said he agreed to “approve or remove holds on foreign military financing and sales of military equipment to Egypt” in exchange for bribes.
Menendez has also accused of revealing sensitive, non-public information about US embassy staff in Cairo to his co-defendants, who then passed the message along to an Egyptian government official.
Those co-defendants include Egyptian-born businessman Wael Hana; Jose Uribe, a New Jersey real estate developer; and Fred Daibes, who works in insurance and trucking.
In addition, the indictment alleges Menendez used his official position to interfere with criminal prosecutions that would have otherwise disadvantaged his co-defendants.
He was originally charged in September with conspiracy to commit bribery, conspiracy to commit honest services fraud and conspiracy to commit extortion. The latter two counts carry a maximum sentence of 20 years a piece.
But the September indictment is not Menendez’s first brush with corruption charges.
In 2015, he faced an 11-week trial over separate accusations that he used his government office to offer favours to a Florida donor, in exchange for bribes. Menendez was never convicted, though: The trial ended in deadlock.
Still, the latest allegations have renewed calls for Menendez to leave his Senate post. His fellow senator from New Jersey, Cory Booker, joined those calls in September.
“Stepping down is not an admission of guilt but an acknowledgment that holding public office often demands tremendous sacrifices at great personal cost,” Booker wrote in a statement. “I believe stepping down is best for those Senator Menendez has spent his life serving.”