A federal appeals court on Friday refused to throw out the bribery and fraud charges filed against U.S. Sen. Robert Menendez, clearing a hurdle standing between the New Jersey Democrat and a possible corruption trial.

Menendez had sought to have his case dismissed, citing constitutional protections that shield the work of legislators from Justice Department interference.

He is accused of accepting nearly $1 million in campaign donations and bribes from a South Florida eye doctor seeking help in disputes with the Obama administration.

But in ruling Friday, a three-judge panel of the Philadelphia-based U.S. Court of Appeals for the Third Circuit rejected that argument. It held that the influence Menendez allegedly exerted to help his benefactor did not fall under the umbrella of protected legislative acts.

"Sen. Menendez does not prevail because the acts alleged in this case were essentially lobbying on behalf of a particular party and thus, under the specific circumstances here, are outside the constitutional safe harbor," Judge Thomas L. Ambro wrote on behalf of the panel.

Lawyers for Menendez, 62, vowed an immediate appeal - first before a full panel of the appellate court and then, if necessary, the U.S. Supreme Court.

"Today's ruling by the Third Circuit Court of Appeals is just another step in the legal process that, at the end of the day, will show that Sen. Menendez has always acted in accordance with the law," attorney Abbe David Lowell said in a statement. "Once all the facts are heard, the senator remains confident that he will be vindicated."

Menendez is accused of accepting campaign donations, private jet flights, and vacations from ophthalmologist Salomon Melgen in exchange for using his office to help the eye doctor in an $8.9 million Medicare-billing fight, an overseas business dispute, and obtaining visas for the man's girlfriends.

Prosecutors say he met with Obama administration officials to suggest policy changes that would directly benefit Melgen.

In arguments before the Third Circuit in February, Lowell contended that the senator set up those meetings not to push action on Melgen's behalf but rather as a part of his congressional duty of legislative oversight.

During them, he pursued broad policy discussions - conversations that are fully covered under the constitutional provision known as the "speech and debate" clause, Lowell maintained.

The protection was instituted to shield lawmakers from the possible threat of a president or other executive branch officials using their power over federal law enforcement to intimidate members of Congress. It bars prosecutors from using any of a legislator's official acts as the basis for an indictment or as evidence in a criminal trial.

U.S. Rep. Chaka Fattah (D., Pa.) similarly turned to such a defense in his efforts to have his corruption case tossed before his conviction this year on racketeering conspiracy, bribery and fraud charges.

However, in a 1972 opinion, the U.S. Supreme Court ruled that the "speech and debate" exceptions were not intended "to make members of Congress super-citizens, immune from criminal responsibility."

Ambro quoted that opinion in the appellate court's ruling Friday in rejecting the senator's arguments.

"That Sen. Menendez framed those meetings using the language of policy does not entitle them unvaryingly to speech or debate protection," Ambro wrote. "Rather, for every mention of policy concerns there is substantial record support for the District Court's findings that those concerns were instead attempts to help Dr. Melgen."

The court ruled it would be up to a jury, should the case proceed to trial, to determine Menendez's motives in setting up those meetings.

Friday's decision comes a month after the Supreme Court overturned the bribery conviction of former Virginia Gov. Bob McDonnell, deciding that actions he took to help a businessman who had given him luxury gifts might have been objectionable but did not meet the legal definition of bribes.

The ruling is expected to have wide implications in public corruption cases moving forward, though they were not part of the arguments Menendez's lawyers made before the Third Circuit.

In his statement, Lowell, Menendez's lawyer, said the McDonnell case "raises equally important issues with [this case] that were not examined here and also will now have to be addressed."

"Once all the facts are heard," he said, "the senator remains confident that he will be vindicated."