For the third time in six months, Senator Robert Menendez stood before a judge in Manhattan on Monday to be formally arraigned on charges in an expansive federal bribery case. He pleaded not guilty, just as he had twice before.

“Once again — not guilty, your honor,” Mr. Menendez told the judge, Sidney H. Stein of Federal District Court.

Mr. Menendez, a Democrat from New Jersey, has previously pleaded not guilty to accepting bribes in exchange for political favors and acting as an unregistered agent of a foreign government.

On Monday, he pleaded not guilty to obstruction of justice, a charge added last week in an updated indictment.

His wife, Nadine Menendez, also pleaded not guilty to obstructing justice. Two New Jersey businessmen accused of bribing the couple with gold bars and hundreds of thousands of dollars, Wael Hana and Fred Daibes, similarly reiterated their not-guilty pleas.

The appearance of the four defendants was brief and largely perfunctory, but the senator, 70, and Ms. Menendez, 57, were surrounded by news cameras as they exited the building in silence and climbed into a waiting car.