Democrat Sen. Bob Menendez (NJ) showed up Monday to a Manhattan federal court for the start of his bribery and corruption trial, which is expected to last months and possibly affect the balance of power in the Senate.

Menendez and his Nadine wife are facing charges that they accepted bribes from businessmen and the governments of Egypt and Qatar in exchange for political favors by Menendez.

Nadine Menendez is being charged separately from her husband.

A search of their home uncovered $500,000 in cash hidden in various locations, 13 gold bars, and a luxury Mercedes-Benz convertible. Prosecutors claim the cash and items were payments in the scheme.

What will happen

Two New Jersey businessmen, Wael Hana and Fred Daibes, were also charged in the case. All four have pled not guilty.

The charges have put Menendez's Senate seat in play for November. He has held the seat since 2006 and was chair of the Foreign Relations Committee until he was indicted, when he was stripped of the position.

Menendez said that if he is found not guilty, he may run for re-election as an independent.

Polls show that his replacement for the Democrat nomination, Rep. Andy Kim, leads with voters over him at this point.

Pivotal seat

The other senator from New Jersey, Cory Booker (D), has called on Menendez to resign, as have others on both sides of the aisle.

The seat is a pivotal one, with Democrats holding only a 51-49 majority in the chamber going into the November election. If he is found guilty before the end of his term, he could be removed from office and cause Democrats to narrow their majority to 50-49.

It's the second time Menendez has been criminally charged with bribery and corruption. The first case in 2017 ended in a mistrial because the jury could not agree on a verdict, and may have emboldened him to continue any wrongdoing he may have allegedly been involved in.

In this trial, another businessman Jose Uribe who was charged in the scheme has pled guilty in March to bribing Menendez and his wife and is cooperating with prosecutors.

His defense

Menendez claims that the cash and gold found in his house is due to "traumatic experiences in his past associated with cash and finances," including the death by suicide of his father after that man incurred large gambling debts that Menendez eventually stopped helping him pay.

The defense has requested that a psychologist testify at the trial about Menendez's trauma and his alleged compulsive habit of storing large amounts of cash in his home.