New Jersey Democratic Sen. Robert Menendez’s public corruption trial is set to begin Wednesday in Newark, New Jersey. The senator has been indicted on federal corruption charges linked to gifts prosecutors alleged were given to him by  Florida doctor Salomon Melgen, his longtime friend, in return for political favors.

Prosecutors suggested that the two men’s relation was a "corrupt pact" in which Melgen provided Menendez with expensive vacations and campaign donations in exchange for the senator helping Melgen in several disputes with government officials.

The case would likely have a major political impact since it's the first time in nearly four decades, a sitting U.S. senator has been indicted. Menendez was indicted in 2015, the New York Times reported.

The trial is scheduled to take place more than two years after charges had been initially filed against the senator and his alleged co-conspirator, Dr. Salomon Melgen.

Menendez, a longtime Congressman was appointed to the Senate in 2006 and the allegations started soon after his election. Menendez was elected to the Senate when then Sen. Jon Corzine was elected as New Jersey’s governor. Menendez served the remainder of Corzine’s term and also has been re-elected two more times since. He served as Chairman of the Senate Foreign Relations Committee in the 113th Congress since 2006. In April 2015, after the indictment, Menendez temporarily stepped down from his position in order to fight the charges, according to his biography on the Senate government website.

After the allegations began in 2006, Melgen’s defense attorneys claimed that the doctor only acted out of his friendship with the senator and as his supporter. It was alleged that Melgen paid for flights as Menendez flew on a private jet to and from his Dominican Republic villa for weekend getaways. Prosecutors also said that Melgen donated hundreds of thousands of dollars to Menendez’s campaign funds, legal defense funds and to political action committees that supported the senator, according to court documents, the Washington Post reported.

In exchange for the money, prosecutors alleged that Menendez acted in his "official capacity" as a senator in order to help advance the personal and business interests of the doctor.

A 2010 trip to the Dominican Republic that was paid for by Melgen has been at the center of the investigation and it was alleged that when word of that trip was leaked in 2013, Menendez paid back $58,000 to Melgen and claimed it was an "oversight" that he had not paid his friend back earlier, CNN reported.

Menendez was under investigation by the FBI in 2013 after an anonymous tipster reached out to media outlets and the FBI and claimed that the senator had been paying for underage prostitutes while on his trips to the Dominican Republic. Those allegations were proved to be false; however, it sparked the government to look closely into the senator’s relationship with Melgen.

Both Menendez and Melgen have been denying the allegations and have explained that they are just old friends who have exchanged expensive gifts with each other and that the senator was only treating Melgen as any other constituent in need.

"I’m angry and ready to fight," Menendez told his supporters the night of the indictment in April 2015, according to the Washington Post.

"That’s one thing that makes this case interesting: It asks the existential question as to when friendship ends and corruption begins," said Robert Mintz, a former federal prosecutor from the U.S. attorney’s office in Newark, according to the New York Times.

Menendez completed his graduation from St. Peter's College in Jersey City, New Jersey, and received his law degree from Rutgers University. Menendez divorced his first wife, Jane Jacobson, in 2005 and married his second wife, Alicia Mucci in 2013. He has two children with his first wife — daughter Alicia and son Robert.