NEWARK, N.J. — A defiant New Jersey Sen. Bob Menendez declared that he’s “not going anywhere” after he was charged with accepting nearly $1 million in gifts and campaign contributions from a longtime friend in exchange for a stream of political favors.

Menendez is expected to appear in federal court in Newark today in response to charges that he used the power of his Senate seat to benefit Dr. Salomon Melgen, a wealthy Florida eye doctor who prosecutors say provided the senator with luxury vacations, airline travel, golf trips and tens of thousands of dollars in contributions to a legal-defense fund.

The indictment, which marks the latest development in a federal investigation that came into public view when federal authorities raided Melgen’s medical offices in 2013, will almost certainly lead to a drawn-out legal fight between Menendez and a team of Justice Department prosecutors who have spent years investigating his ties to Melgen.