An investigative jury has indicted Democratic Senator Robert Menendez on charges including conspiracy to commit bribery and wire fraud.
The New Jersey senator has been charged with using his office to improperly benefit an eye doctor and a political donor.
Menendez was indicted in New Jersey along with Florida ophthalmologist Dr. Salomon Melgen on one count of conspiracy, one count of violating the travel act, seven counts of bribery and three counts of honest services fraud, a US Justice Department spokesman said, adding the senator was also charged with one count of making false statements.
The agency said Menendez "allegedly accepted gifts from Melgen in exchange for using the power of his Senate office to benefit Melgen's financial and personal interests."
Prosecutors had been looking into whether Menendez improperly advocated for the business interests of Dr Salomon Melgen, including by intervening on the doctor's behalf in a medical billing dispute.
Menendez has acknowledged that he flew on Melgen's private plane to the Dominican Republic and failed at first to properly pay for the trips. He later made reimbursements.
Menendez has previously said he has done nothing wrong and that he and Melgen have been close friends for a long time.
Menendez would be only the second US senator to face a federal corruption indictment in the last 20 years.
Menendez, who is Cuban-American, is among the most senior Hispanic politicians in the country. He was re-elected to a second term in the Senate in 2012. He spent 13 years in the US House of Representatives.