Sen. Bob MenendezRobert (Bob) MenendezOvernight Health Care: House passes 20-week abortion ban | GOP gives ground over ObamaCare fix | Price exit sets off speculation over replacement You want to recall John McCain? Good luck, it will be impossible Poll: Most in NJ want Menendez to resign if found guilty MORE (D-N.J.) sponsored legislation that would have financially benefited his close friend and political donor Dr. Salomon Melgen, according to an Associated Press report released Monday.

Melgen, a Florida eye doctor, in 2010 invested at least $51,500 in a natural-gas company, Gaseous Fuel Systems Corp., that sells products to allow companies to convert diesel-fuel fleets to natural gas. 

At the same, the AP reports that Menendez emerged as a primary advocate for a bill that would boost tax credits and grants to companies that converted their vehicle fleets to use alternative fuels. 

The bill failed to make it out of the Senate, but Melgen reportedly spent $220,000 lobbying Menendez’s staff and other congressional officials to pass the legislation.

A spokeswoman for Menendez disputed the AP report, and said Menendez only pursued the legislation because it would “reduce air pollution, increase energy security, and lower transportation costs.”

“This bill, which is consistent with policies embraced by President Obama, would have affected dozens of companies and millions of individuals all across America, and the suggestion its introduction stemmed from one small company is preposterous,” spokeswoman Tricia Enright told The Hill in an email. “Senator Menendez introduced this legislation to help improve our environment, our economy, and our security and it was only defeated because a collection of special interests led by the Koch brothers rallied against it.”

Enright also said the senator's involvement with the bill preceded Melgen's reported investment.

The allegation in the AP report is the latest involving Menendez’s ties to Melgen, whom he has described as “a friend and political supporter.” Menendez has steadfastly maintained his innocence against charges that he has improperly helped Melgen.

Melgen is under investigation for reportedly over-billing the U.S. government by almost $9 million, inviting a federal audit. Menendez has acknowledged he contacted officials on two occasions to complain that the billing rules were unclear and that the doctor was being treated unfairly in the case. 

The senator denied that his close ties to Melgen had anything to do with him raising the issue. Melgen has been ordered to repay the money, but his appeal is ongoing.

The Senate Ethics Committee is also looking into claims that Menendez acted improperly by flying to the Dominican Republic on Melgen’s private plane. 

Menendez recently reimbursed Melgen’s company $58,500, the cost of two previously undisclosed trips from personal funds, after a complaint filed by the New Jersey Republican Party alleged that the senator had failed to account for some flights.

Melgen contributed to Menendez’s campaign and took him on at least three trips to the Dominican Republic aboard his private plane in 2010.

The conservative Daily Caller website has also alleged Menendez had sex with Dominican prostitutes on those trips. 

Menendez denies the allegations of sexual impropriety, saying they were manufactured ahead of his election last November.

“The smears that right wing blogs have been pushing since the election, that is totally unsubstantiated — it's amazing to me that anonymous, nameless, faceless individuals on a website can drive that kind of story into the mainstream,” Menendez has said. “The bottom line is all of those smears are absolutely false.” 

News of the Senate ethics panel's interest in Menendez's connection to Melgen came after another report that the New Jersey Democrat pressed members of the Obama administration to lift restrictions on a massive port-security contract to help his friend. 

The Miami Herald reported on an exchange from a July hearing of the Foreign Relations Committee in which Menendez referenced a contract the government of the Dominican Republic had awarded to a company owned by Melgen.

Melgen’s home was raided by the FBI earlier this month. It is unclear whether the FBI’s investigation of Melgen is targeting him for outstanding back taxes, his political contributions to Menendez and other lawmakers, or allegations over engaging with prostitutes.

This story was updated at 12:15 p.m. with a statement from the office of Sen. Menendez.