Sen. Bob Menendez is embroiled in a prostitution scandal — and it has little if anything to do with sex.

The New Jersey Democrat has for three months been the target of voluminous allegations, all unconfirmed, that he hired prostitutes, one reportedly underage, in the Dominican Republic and other places.

Menendez, the new chairman of the Senate Foreign Relations Committee, has angrily denied the allegations as they bubbled up into the mainstream media.

But, proving that the political gods do have a sense of humor, the Senate chose this exact moment — as Menendez fights for his political life — to take up two pieces of legislation on human trafficking, including one on child sex trafficking.

“This cuts across party lines, all philosophical lines,” Sen. Rob Portman, R-Ohio, said of his proposal. “It’s about basic human dignity.”

Sen. Richard Blumenthal of Connecticut, the legislation’s Democratic co-sponsor, said on the Senate floor Monday that it is “an unacceptable and intolerable fact that sex trafficking is a major source of child exploitation, a major source of damage to our children, and the voices and faces of those children should be before this body.”

The awkward timing of the votes has made matters even more difficult for Menendez, who was slinking about the Capitol on Monday, avoiding reporters and colleagues. The juxtaposition has produced some backroom snickering in the Senate, and Menendez deserves the ridicule — but for reasons unrelated to the claims. Menendez deserves opprobrium, some would argue, because he has acted like a prostitute himself.

There is no evidence that the squat 59-year-old is selling his body, thank heavens. But there have been allegations that he has been selling his influence and demeaning the body politic.

Menendez is facing a Senate ethics investigation of two free trips he took in 2010 aboard the private plane of a donor, Salomon Melgen, to a luxury resort in the Dominican Republic. After news of the jaunts became public recently, Menendez reimbursed Melgen $58,500.

The senator and his various political entities have received almost $50,000 from Melgen and his family, who also gave $700,000 to a super PAC created to elect Senate Democrats.

As it turns out, Menendez performed certain acts for his benefactor.

The Washington Post’s Carol D. Leonnig and Jerry Markon reported last week that Menendez twice questioned federal health care officials about their finding that Melgen, an eye doctor, had overbilled the government on Medicare claims. FBI agents and health care investigators recently raided Melgen’s eye clinic in Florida.

The New York Times reported Monday that Menendez intervened with the Homeland Security Department to prevent the United Sates from donating port security equipment to the Dominican Republic. The donation threatened to upend an arrangement for Melgen-related interests to do the work.

Menendez’s office had earlier urged the State Department to push Dominican officials to honor the port security contract, which is worth as much as $500 million over 20 years and had been awarded to a company with connections to Melgen.

It’s up to the ethics committee to determine whether Menendez broke the rules. But allegations of a quid pro quo between donor and lawmaker are notoriously difficult to prove. In Washington, this kind of prostitution is legal.

In the Dominican Republic, the original kind of prostitution is legal. But that won’t spare Menendez a bit of awkwardness whenever the subject is raised.

Now, with the Senate taking up two proposals involving human trafficking (both amendments to the Violence Against Women Act), is one such awkward moment.

Menendez wasn’t on the floor Monday as Sen. Patrick Leahy, D-Vt., sponsor of one of the proposals, said human trafficking “amounts to modern-day slavery.” During a vote on an unrelated amendment Monday night, Menendez was already keeping to the shadows.

Ten minutes after the roll was called, he entered the chamber from a back door. He took three paces onto the floor, signaled his no vote, and disappeared just as quickly through the same door.

Without a word to colleagues, he slipped down a back staircase and stole out of the building and into the dark of night.

Dana Milbank is a columnist for The Washington Post Writers Group. He can be contacted at:

danamilbank@washpost.com