Sen. Robert Menendez (D-N.J.) is denying allegations that a major donor supplied him with free trips to the Dominican Republic where he engaged with underage prostitutes.

Those accusations, reported on conservative Web sites before the 2012 election, have resurfaced due to an FBI raid on the home of Dr. Salomon Melgen, a Menendez contributor. The doctor faces a $11.1 million IRS lien for unpaid taxes. 

"Dr. Melgen has been a friend and political supporter of Senator Menendez for many years," Menendez's office said in a statement Wednesday. "Senator Menendez has traveled on Dr. Melgen's plane on three occasions, all of which have been paid for and reported appropriately. Any allegations of engaging with prostitutes are manufactured by a politically-motivated right-wing blog and are false."

NBC News reports that Menendez recently wrote a $58,000 personal check to cover two of those flights.

The Daily Caller, a conservative Web site, has published e-mail exchanges in which a tipster tells FBI agent Regino Chavez that Menendez has had contact with underage prostitutes. The agent says they are investigating. (According to the Miami Herald, the e-mails are legitimate.) In those e-mails, the tipster repeatedly puts off in-person or telephone meetings with both Chavez, and reporters from Citizens for Responsibility and Ethics in Washington and ABC News. He also resists their attempts to establish direct contact with the alleged prostitutes.

Senate Majority Leader Harry Reid (D-Nev.) dismissed the reports on Tuesday, saying "all anyone here has to look at it is the source where this comes from."

The allegations come as Menendez takes on not only a high-profile role in the "Gang of Eight" that will attempt to pass bipartisan immigration reform in the Senate, but also chairmanship of the Senate Foreign Relations Committee.