WASHINGTON — U.S. Sen. Robert Menendez — who evolved from a scrappy New Jersey politician to one of the nation's leading voices in foreign affairs — was charged in a 14-count indictment Wednesday that accuses him of intervening on behalf of a wealthy friend and campaign donor in exchange for luxurious gifts and vacations.

The indictment announced by the federal Justice Department focused on Menendez's actions on behalf of his friend and benefactor, Dr. Salomon Melgen, a West Palm Beach, Fla., ophthalmologist, who also faces criminal charges.

The two men were indicted on one count of conspiracy, one count of violating the travel act, eight counts of bribery and three counts of honest services fraud. Menendez, a Democrat, was also charged with one count of making false statements.

"Government corruption — at any level of elected office — corrodes the public trust and weakens our democratic system," Assistant U.S. Attorney General Leslie Caldwell said in announcing the indictments. "It is the fundamental responsibility of the Department of Justice to hold public officials accountable by conducting thorough investigations and seeking an indictment when the facts and the law support it."

MORE MENENDEZ COVERAGE:

• Editorial: Menendez should resign

• Inside the indictment

• Lawmakers, critics react

• Who is Salomon Melgen?

• Quick look at Menendez's life and career

• Timeline of investigations involving Menendez

Menendez, 61, said he would give up his position as ranking member of the Senate Foreign Relations Committee, from which he pushed for increased sanctions to force Iran to curb its nuclear program and raised his voice against President Obama's efforts to restore diplomatic relations with Cuba. At the recent American Israel Public Affairs Committee's national convention, Menendez pledged that Iran would "never threaten Israel or its neighbors, and it will never be in a position to start a nuclear arms race in the Middle East. Not on my watch."

A defiant Menendez told a cheering crowd at the Newark Hilton that he did nothing wrong.

"I'm confident at the end of the day I will be vindicated," Menendez said. "This is not how my career is going to end.''

Menendez, who did not take questions after his statement in English and Spanish, said that the Justice Department turned a friendship into a corruption case.

"I'm not going anywhere," Menendez said. "I'm angry and ready to fight because today contradicts my public service career and my entire life."

The charges threaten to topple New Jersey's senior U.S. senator and one of the most powerful members of the state's congressional delegation. Menendez built ties to the Senate Democratic leadership and gained support among his colleagues during his tenure as chairman of the Democratic Senatorial Campaign Committee.

The indictment follows a years-long probe of the relationship between Menendez and Melgen. It charges that the senator received close to $1 million in gifts and campaign contributions from Melgen, 61, from January 2006 to January 2013 in exchange for intervening with the government on his behalf.

It provides new details about Menendez's actions on behalf of Melgen and the gifts he received.

For example, it is known that Menendez had contacted the Centers for Medicare and Medicaid Services, which found that Melgen had overbilled the government by $8.9 million, and that the senator asked about a port-security contract in the Dominican Republic held by a company whose investors include Melgen.

The indictment mentions a third time that Menendez helped Melgen, when he supported applications for visas for several of the doctor's girlfriends.

Melgen contributed $700,000 to a super-political action committee aligned with then-Senate Majority Leader Harry Reid (D-Nev.) in 2012. The super-PAC, in turn, spent $580,500 on Menendez's re-election, according to the Center for Responsive Politics, a Washington-based research group. The indictment said Melgen earmarked $600,000 specifically for Menendez's race.

He and his family also contributed $40,000 to Menendez's legal defense fund. In addition, the indictment said, Melgen contributed to an unnamed Senate candidate at Menendez's request to help the senator meet his commitment to raise money for his colleague. Though the other senator's name was not mentioned, Melgen and his wife gave $8,000 to Sen. Amy Klobuchar (D-Minn.) on Aug. 8, 2012, according to the Center for Responsive Politics.

Emails to Klobuchar's office were not returned, but the Atlantic reported that the senator would give back the contributions.

Menendez never disclosed any of the gifts that he received from Melgen on his financial disclosure forms, the Justice Department said. The senator later acknowledged the flights aboard Melgen's private plane and reimbursed him $69,750; $58,500 from his personal funds and $11,250 from his campaign account.

Besides those trips, the indictment said, Melgen opened his Dominican Republic villa to Menendez and his guests, including assigning a staff member to attend to their needs.

There were also other Melgen-paid trips that had not been reported before, including three nights at a five-star Paris hotel, an extended weekend at a resort in the Dominican Republic, and a round of golf at a private club in West Palm Beach, according to the indictment.

U.S. Rep Albio Sires (D-8th Dist.), like Menendez a member of the Congressional Hispanic Caucus, quickly issued a statement in support of the senator.

"All Americans, not just Senator Menendez, are entitled to a presumption of innocence," Sires said. "These charges are just an accusation. My good friend, Bob Menendez is not going anywhere. I know that he will get through this and nothing will distract him from doing what he does best, fighting for New Jersey."

New Jersey's junior U.S. senator, Cory Booker, a fellow Democrat, also backed Menendez.

"Our system of justice is designed to be fair and impartial, and it presumes innocence before guilt," Booker said. "I won't waver in my commitment to stand alongside my senior Senator to serve our great state. Our nation and state face critical issues and I will continue to partner with Senator Menendez to take on the challenges before us."

Republican Gov. Chris Christie said only, "Everybody deserves the presumption of innocence and there's no reason for me or anybody else to get out ahead of themselves."

But a nonprofit group partially funded by an organization with ties to billionaire energy executives Charles and David Koch renewed its call for Menendez to step down.

"He has now been formally indicted on public corruption charges by a grand jury and cannot represent the people of New Jersey," said Phil Kerpen, president of American Commitment.

Menendez is the 12th U.S. senator to be indicted while in office.

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Jonathan D. Salant may be reached at jsalant@njadvancemedia.com. Follow him on Twitter @JDSalant. Find NJ.com Politics on Facebook.