New Jersey Sen. Bob Menendez is at the apex of his career, the highest-ranking Hispanic in congressional history as chairman of the Senate Foreign Relations Committee and one of the “Gang of Eight” senators leading the charge for immigration reforms.

Not bad for the son of pre-Castro Cuban migrants — his mother a seamstress, his father an odd-jobs carpenter — who grew up in a Union City tenement and was the first member of his family to go to college.

Menendez, 58 and a Democrat, today faces several serious allegations for his links to Salomon Melgen, a West Palm Beach eye doctor and wealthy donor under investigation by the FBI.

But the veteran of New Jersey’s rough-and-ready politics, who once claimed he put on a bulletproof vest to testify against his former political mentor in a racketeering trial, has vehemently denied any wrongdoing and is expected to fight back vigorously.

“He is known as one tough hombre. You do not want to get cross-ways with him because he doesn’t suffer fools gladly and his mind is razor-sharp, and he will cut you to the quick,” said Washington lobbyist and Menendez campaign donor José Cardenas.

Menendez also has strongly supported U.S. sanctions on Cuba, and been singled out as the key obstacle to the possibility that the Obama administration might try to improve relations with Havana in the next four years. During the custody battle over Elián González in 2000, Menendez proposed making him a U.S. citizen. And in 1996 he pushed the Helms-Burton Act to tighten the U.S. embargo.

“From the day he was elected to Congress, Bob’s voice has been consistent and determined to shed light on the abuse of this totalitarian regime and to do all he could to have human rights be respected in Cuba,” said Rep. Ileana Ros-Lehtinen, the Miami Republican.

But he also has defended abortion rights, favored affirmative action and gun controls, voted against authorizing President Bush to invade Iraq and backed Hispanics when they were under attack by such figures as Lou Dobbs and Rush Limbaugh.

“One of my goals is to guide all Americans toward a new understanding of Latinos in this country, to assert once and for all that we are full participants in the dream, not some recently arrived crowd imposing a foreign culture,” he wrote in his 2009 book, Growing American Roots.

He has been chairman of the House Democratic Caucus — the third-highest party job in the chamber — head of the fundraising Democratic Senatorial Campaign Committee and now sits on the bipartisan group of senators negotiating immigration reforms.

But the peak of his career came two Fridays ago when he became chairman of the Senate Foreign Relations Committee, a powerful and prestigious post previously held by John Kerry, D-Mass., who was sworn in as secretary of state around that same time.

Menendez’s record is not without blemishes, and The New York Times endorsed his Senate candidacy in 2006, writing that he was the best candidate despite “a history of ethical lapses that have been all too common for Democratic officials in New Jersey.”

In his latest scrape, he repaid Melgen $58,500 on Jan. 4 for two private trips to the Dominican Republic in 2010, trips not disclosed until long after a tipster using the alias of “Peter Williams” began making accusations last summer.