New Jersey Democratic Sen. Bob Menendez entered the first day of his corruption trial Wednesday on the verge of tears, as he proclaimed his innocence outside federal court in Newark.

"I appreciate my family, my son and daughter being here today and appreciate all my supporters," he said.

Emotions ran high, but the stakes are even higher, with Menendez facing a dozen criminal charges.

It's the first time a sitting senator has faced a federal bribery trial in 36 years – not only is his career and reputation on the line, but the trial could affect the balance of power in the U.S. Senate, where Republicans are eager to pad their slim majority.

The opening day featured dramatic allegations, including that Menendez "sold his office for a lifestyle he couldn't afford,” and testy exchanges – with District Court Judge William H. Walls at one point telling Menendez’s lawyer to “shut up.”

Menendez is accused of accepting more than $700,000 in campaign-related cash and thousands of dollars in free hotel rooms and air travel from a longtime friend, Dr. Salomon Melgen. Melgen is charged with 11 counts.

During opening statements on Wednesday, prosecutors told the jury that as part of the bribery scheme, Menendez sent the doctor an email asking him to provide a $1,500-dollar-a-night Paris hotel room with a limestone bath and a view of the courtyard.

Federal prosecutors say "the evidence will show Menendez went to bat for Melgen at the highest levels of government because he gave him access to a lifestyle that reads like a travel brochure for the rich and famous."

Prosecutors say Menendez, in exchange, helped the doctor with multimillion-dollar business deals and allegedly tried to get visas for the doctor’s foreign girlfriends.

Both Melgen, who has a previous conviction for Medicare fraud, and Menendez are on trial.

Aside from the implications for the balance of power in the Senate, the trial also poses complications for upcoming Senate votes.

The judge earlier rejected a motion from Menendez to change the trial schedule to allow him to attend crucial votes on issues such as health care. In a testy exchange Wednesday, Menendez's attorney accused the judge of disparaging the defense in his written opinion. At one point, the judge told Menendez's lawyer, "Shut up for a moment, if you don't mind."

Menendez says he will exercise his constitutional right to attend his trial but acknowledged the conflict he faces if Democrats need his vote in the Senate. "When a conflict exists, the clash between those constitutional rights, I will make a decision based upon the gravity of the situation and the difference that my vote would make,” he said.

The defense contends this is not about corruption or bribery but about a long-term friendship.

During his opening statement, Menendez's lawyer told jurors "a single word can cut through a mountain of evidence" – that word being friendship.

The trial is expected to last six weeks.