Though he has yet to officially declare his candidacy, Mr. Menendez has given no sign that he plans to step down, and on Thursday he vowed to confront those who sought to take advantage of the political damage caused by the trial.

“To those who were digging my political grave so that they could jump into my seat, I know who you are and I won’t forget you,” Mr. Menendez said.

Officials with the United States Department of Justice said they will wait to decide whether to retry Mr. Menendez and his co-defendant, Dr. Melgen, 63, though they will likely take into account that most of the jurors favored an acquittal. “The department will carefully consider next steps in this important matter,” said Nicole Navas Oxman, a spokesman for the agency.

One juror told reporters that the jury was never close to a consensus on the charges.

“It was very tense. We were deadlocked right out of the gate,” said the juror, Ed Norris, 49, an equipment operator from Roxbury Township, who said he believed the men were not guilty.

“I just wish there was stronger evidence,” he said. “I just didn’t see a smoking gun. They just didn’t prove it to us.”

Still, Republicans will undoubtedly seek to make any re-election effort for Mr. Menendez difficult, forcing Democrats to invest resources in a blue state. After the mistrial, Senator Mitch McConnell, the Republican majority leader, said in a statement that he was “calling on the Senate Ethics committee to immediately investigate Senator Menendez’s actions, which led to his indictment.’’