Jurors in the bribery trial of New Jersey Sen. Bob Menendez sent the judge a note on Monday saying they "can't reach a unanimous verdict on any of the charges."
The judge excused the jurors and told them to return Tuesday to continue deliberating the Democratic senator's fate.
A juror who was excused from the trial on Thursday gave a glimpse into deliberations, saying that most jurors favored acquittal and that she would have cast a not-guilty vote on all counts.
The excused juror, Evelyn Arroyo-Maultsby, spoke outside the courthouse after the jury was unable to reach a verdict after three full days and part of a fourth. The judge in August approved her leaving because she had a trip planned for a family wedding.
"I think the defense showed me enough to say he's not guilty on every count," she said.
Arroyo-Maultsby was replaced by an alternate, and jurors resumed deliberations Monday for a few hours before reporting they were deadlocked.
The trial was the first in 36 years to involve a sitting senator on federal bribery charges, the most serious of which carries a 20-year maximum prison sentence.
During arguments in Newark, New Jersey, prosecutors painted Menendez, 63, as the "personal senator" to Florida ophthalmologist, Dr. Salomon Melgen.
Melgen, who was on trial alongside Menendez, was found guilty in April of health care-related fraud.
Prosecutors in the Menendez case said Melgen had offered his private jet for the two-term senator's use, showered him with luxury trips and steered more than $750,000 in campaign contributions to entities supporting Menendez.
Menendez reciprocated by aiding Melgen's business interests, prosecutors added, including helping him with a Medicare billing dispute and obtaining visas for foreign women described as Melgen's girlfriends.
Defense attorneys said Menendez's meetings on behalf of Melgen were to discuss policy issues, and various trips to the Dominican Republican were merely social visits.
"They are lying to you," Melgen's attorney, Kirk Ogrosky, told jurors in closing arguments last week. "They're making up a story and trying to get the evidence to fit their story."
Both defendants initially pleaded not guilty in 2015 to 18 counts of bribery and fraud. Neither took the witness stand.