(CNN) – The allegations of misconduct swirling around Sen. Robert Menendez – which he has vehemently denied – appear to have eroded the New Jersey Democrat's approval rating, according to a survey released Thursday.
The Quinnipiac University poll indicated that 41% of New Jersey voters disapproved of the job Menendez is doing as senator, compared to 36% who approve. That's a 15-point drop from a poll taken toward the end of January, when 51% approved of Menendez's job performance. Quinnipiac said it's his lowest approval rating since August 2011.
Menendez has vigorously defended himself against claims by unidentified accusers who he says are "trying to defame" him with accusations that he improperly used his office. The allegations include a charge that he accepted unreported plane flights, advocated on Capitol Hill on behalf of a business, and intervened in a Medicare billing inquiry.
Last month, Menendez paid approximately $58,500 to a friend and campaign donor for several flights he took in 2010, chalking up the lapse in payment to his busy schedule.
He has denied wrongdoing relating to a number of the claims, including in an exclusive television interview with CNN Chief Congressional Correspondent Dana Bash. "The bottom line is all those smears are absolutely false," he said, describing claims that he had partied with prostitutes "unsubstantiated."
In Thursday's poll, 70% of New Jersey voters said they had read or heard something about the controversy involving Menendez. Fifty-nine percent of those said they allegations made them feel less favorably about the senator, and 35% said the charges didn't affect how they felt about Menendez.
"U.S. Sen. Robert Menendez took an overseas trip and the poll numbers he left behind in New Jersey are dreadful – down 15 points in less than a month," said Maurice Carroll, director of the Quinnipiac University Polling Institute. "So much for a reelection honeymoon."
And what about the Garden State's other U.S. Senate seat? Last week the current occupant, longtime Democratic Sen. Frank Lautenberg, said he wouldn't seek re-election in 2014.
One Republican who's expressed interest is Fox News host Geraldo Rivera, who said earlier this month New Jersey needed a "modern Republican" like himself in Washington.
Voters in the state seem to disagree – in a potential match-up with Newark Mayor Cory Booker, a Democrat who's also expressed interest in the seat, Rivera is behind by a large margin, 59%-23%.
His favorability rating is also underwater. Thirty-nine percent have an unfavorable opinion of the television personality, compared to 20% who view him favorably and 40% who haven't heard enough about him.
"If TV personality Geraldo Rivera is just testing the water for a U.S. Senate run in New Jersey, he might find that the water is colder than the Atlantic Ocean in February," Carroll said.
The Quinnipiac University poll was conduced by telephone from 1,149 registered voters in New Jersey between February 13 and 17. The sampling error was plus or minus 2.9 percentage points.