Mr Menendez, a Democrat from New Jersey, and his wife, Nadine Menendez, were charged in September with allegedly accepting gifts including cash, gold bars and a luxury car in exchange for the use of the senator’s influence to enrich three New Jersey businessmen and benefit the Egyptian government.
Prosecutors said businessman Wael Hana had arranged meetings between Mr Menendez and Egyptian officials, who pressed the senator to sign off on military aid.
In return, Mr Hana put Mr Menendez’s wife on the payroll of a company he controlled, prosecutors said.
The senator and his wife were also accused of attempting to “cover up” the bribery scheme, as well as trying to repay more than $20,000 worth of bribe money under the guise of loans. The couple allegedly used the money to pay for a Mercedes-Benz and home mortgage payments.
Mr Menendez, his wife and the businessmen have pleaded not guilty to the charges.
In court documents, lawyers for Mr Menendez asked that he and his wife go on trial separately because he “intends to present a defence arguing (in part) that he lacked the requisite knowledge of much of the conduct and statements of his wife, Nadine.”
“By this defense, Senator Menendez’s legal team may have to argue, in effect, that any unlawful conduct — and we are aware of none —involved the actions of others (including Nadine), not the Senator,” his lawyers wrote.
They argued the senator would face a “catch-22” situation if he was forced to go on trial alongside his wife because a joint trial would “force Senator Menendez to make an impossible and prejudicial choice between testifying on his own behalf and exercising his spousal privilege to avoid being converted through cross-examination into a witness against his spouse.”
In a separate motion, lawyers for Ms Menendez also argued that a joint trial would prejudice her right to defend herself at a fair trial.
They argued a joint trial would likely demonstrate an “irreconcilable conflict between husband and wife” and that it would be “unfair to require either spouse to sacrifice the right to testify fully in one’s own defence or the ability to maintain the confidentiality of privileged marital communications.”
The charges Menendez and his wife are facing include conspiracy to commit bribery, conspiracy to commit honest services fraud and conspiracy to commit extortion under color of official right.
The senator was initially indicted alongside his wife in September for allegedly participating in a scheme connected to the Egyptian government, but has since faced two superseding indictments in October and earlier this month relating to a scheme involving Qatar.
The latest indictment alleges Mr Menendez accepted gifts from Fred Daibes, a co-defendant and New Jersey businessman, in exchange for his assistance in securing millions of dollars from an investment fund with ties to the Qatar government.
Mr Menendez allegedly accepted luxury watches, a gold bar and cash, in exchange for introducing Mr Daibes to a member of the Qatari royal family, who was also a principal of the Qatari Investment Company, as well as publicly making positive statements about Qatar.
Federal prosecutors alleged that Mr Menendez accepted the gifts “knowing” that Mr Daibes expected him to “induce the Qatari Investment Company to invest with Dabies” which included “taking action favourable to the Government of Qatar.”
The superseding indictment also alleges a Qatari official provided a relative of Mr Menendez’s wife, Nadine Menendez, with tickets to the 2023 Formula One Grand Prix in Miami – at the request of the New Jersey senator.
The latest allegations, which accused him of acting as a foreign agent, add pressure on the embattled senator, who has resisted calls to resign from members of his own party.
In a senate speech earlier this month, Mr Menendez reiterated his innocence, and insisted he had been a “patriot for and of my country.”