Bob Menendez, D-N.J., after the jury indicated it was deadlocked on all counts.
Prosecutors could refile charges against Menendez, but it is unclear if they will choose to do so.
Prosecutors relied mostly on circumstantial evidence to prove their case - spending the opening weeks of trial painting a jet-setting lifestyle of the rich and powerful before ultimately turning to the "official acts" they argued Menendez did to help his friend.
"Certain elements of the Federal Bureau of Investigation and of our state cannot stand, or even worse, accept that the Latino kid from Union City and Hudson County could grow up to be a United States senator and be honest", said the 63-year-old son of Cuban immigrants.
Menendez said Thursday that the way the case was investigated and the way prosecutors brought charges and tried the case was wrong.
Norris said that after the prosecution rested, "in my gut I was like, 'That's it?"
Defense attorneys said Menendez's meetings on behalf of Melgen were to discuss policy issues, and various trips to the Dominican Republic were merely social visits between friends. Menendez and Florida eye doctor Salomon Melgen were charged with running a bribery scheme between 2006 and 2013 in which Menendez traded his political influence for luxury vacations and flights on the doctor's private plane. Defense attorneys sought to show jurors that the two men are longtime pals who exchanged gifts out of friendship.
"I just wish there was stronger evidence right out of the gate", the juror said.
Gov't asked judge to make partial verdict charge to jury, but judge said it wasn't warranted by note. "I just didn't see a smoking gun".
According to CNN, Menendez was charged with conspiracy, bribery, and honest services fraud related to abusing the power of his office.
According to the government, Menendez also helped secure visas for the married Melgen's foreign girlfriends and asked US officials to resolve a port dispute in the Dominican Republic involving one of Melgen's businesses. In a statement, the Justice Department said it would "carefully consider next steps".
Menendez has already raised more than $2.5 million for re-election this year. "To those who embraced me in my darkest moment, I love you".
The Republicans have a thin, 52-48 edge in the Senate as they try to push through President Donald Trump's agenda.
Deliberations began last week, but the jury restarted Monday after a juror was excused for a previously scheduled vacation and was replaced by an alternate.
The panel first indicated Monday afternoon that they were struggling to reach a verdict, but U.S. District Judge William Walls instructed the jury to keep deliberating.