NEW YORK (Reuters) - Jurors could be seated as soon as Wednesday to determine whether Robert Menendez, New Jersey's senior senator, broke the law in what federal prosecutors called a years-long bribery scheme to benefit Egypt's and Qatar's governments, as well as himself.

The jury selection process will enter its third day in Manhattan federal court.

U.S. District Judge Sidney Stein said on Tuesday that a jury could be empaneled by Wednesday after prosecutors and defense lawyers exercise challenges to seating various jurors. Opening statements would follow.

Menendez, 70, a Democrat, has pleaded not guilty to 16 criminal charges including bribery, fraud, acting as a foreign agent and obstruction.

He is being tried alongside New Jersey businessmen Wael Hana and Fred Daibes. The senator's wife Nadine Menendez, 57, is scheduled to be tried on July 8, with the delay resulting from what her lawyers called a serious medical condition.

All have pleaded not guilty. The bribery trial is Robert Menendez's second, with the first ending in 2017 in a mistrial after jurors deadlocked. Menendez became a senator in 2006.

CASH, GOLD AND A MERCEDES-BENZ

Prosecutors are expected to detail a complex and sordid array of corruption that they say lasted from 2018 to 2023.

The Menendezes are accused of accepting hundreds of thousands of dollars in bribes from Hana, Daibes and insurance broker Jose Uribe, in exchange for the senator's providing political favors and aid to the governments of Egypt and Qatar.

Prosecutors said the senator promised to help Egypt obtain arms sales and other aid, helped Hana obtain a lucrative monopoly on certifying that meat exports to Egypt conformed to Islamic law, and tried to help Daibes secure millions of dollars from a Qatari investment fund.

Menendez also allegedly tried to interfere in a federal criminal case against Daibes in New Jersey, and in state criminal cases involving two of Uribe's associates.

Prosecutors said FBI agents found more than $480,000 of cash in the Menendezes' home, much stashed in clothing, closets and a safe.

Bribes also included more than $100,000 in gold bars, and a $60,000 Mercedes-Benz convertible, prosecutors said.

POLITICAL FALLOUT

Uribe pleaded guilty in March to bribery and fraud, and agreed to cooperate with prosecutors.

While Nadine Menendez will not be on trial now, her husband's lawyers have suggested their defense might include an effort to blame her, saying she withheld information and made him believe his activities were lawful.

The senator has suggested he would try if acquitted to win a fourth full Senate term, but as an independent.

Any reelection bid would be a long shot, reflecting recent polls of voters in Democratic-leaning New Jersey that show overwhelming disapproval of Menendez's job performance.

Menendez has resisted calls to resign from across the political spectrum, but gave up leadership of the powerful Senate Foreign Relations Committee after his indictment in September.

(Reporting by Jonathan Stempel in New York; Editing by David Gregorio)

By Jonathan Stempel