New Jersey's largest newspaper had some tough words Sunday for Sen. Bob Menendez as he faces allegations of improper travel and parties with prostitutes. The same paper endorsed the senator's bid for re-election three months ago.

An editorial in the Newark-based Star-Ledger said the accusations raised "serious doubts about his fitness to serve as Chairman of the Foreign Relations Committee" and argued he "needs to break his silence and explain himself."

The chairmanship had been held by former Sen. John Kerry, who was sworn in as secretary of state on Friday. Menendez is set to take over the position this week.

Menendez has been in the spotlight as scrutiny escalates over his relationship with a generous donor whose plane he took to the Dominican Republic and who has business ties in the Caribbean nation.

The scandal first emerged shortly before Election Day last fall, when a conservative online publication cited three unidentified sources who claimed the senator had flown on private planes to the Caribbean and during the trip had sex parties with prostitutes.

In response to a question Thursday from CNN regarding whether he broke finance laws, Menendez deferred to his office but added "these are nameless, faceless, anonymous allegations. You should find out from them."

The Star-Ledger didn't put much stock in the prostitute claims, saying the allegations have no credible evidence and have "all the markings of a dirty trick."

But it raised questions about the plane trips, which Menendez took in 2010 but didn't pay for until January 4 of this year - a gap that his spokeswoman, Patricia Enright, described as an "oversight." His office said Menendez paid $58,500 from his personal funds.

The Star-Ledger editorial board, however, didn't buy that it was simply an "oversight."

"Why would anyone remember something so routine and mundane as a rich guy whisking you off to an exotic vacation in the Caribbean in a private jet? If the senator has no better explanation, he will richly deserve the reprimand the full Senate will no doubt impose on him," the editorial stated.