Sayfullo Saipov, a native of Uzbekistan who killed eight people in a 2017 terrorist truck attack on a Hudson River bike path, will receive a life sentence in prison after members of a Manhattan federal jury deadlocked as they decided his fate.

The jurors told Judge Vernon S. Broderick on Monday that they could not agree on whether to impose the death penalty as the government had sought. Under the law, a unanimous verdict was required before the jury could impose capital punishment.

The verdict, which came on the jury’s second full day of deliberations, followed a two-month trial in which Mr. Saipov, 35, was convicted on Jan. 26 of all 28 counts he faced.

The trial was the first federal death penalty trial held during the administration of President Biden, who had campaigned against capital punishment. It was also a rare death penalty trial in New York, where executions are even rarer. The last state execution was in 1963; the last federal executions were in the early 1950s.

The jurors, as Judge Broderick had instructed, did not reveal how they were split in their votes, so it was not possible to know how many voted for execution and how many for a life sentence.

Even a single juror holding out against the death penalty would result in an automatic life sentence.

The counts that could have prompted capital punishment included eight of murder in aid of racketeering activity — one for each victim killed — and one of violence and destruction of a motor vehicle causing death.

Prosecutors, in seeking Mr. Saipov’s execution, cited such factors as his premeditation and planning, his lack of remorse, the future danger he would pose in prison and that he carried out the attack to further the ideological goals of ISIS.

Mr. Saipov was portrayed by his lawyers during the trial as a loner who had become radicalized by Islamic State propaganda, consuming endless hours of violent martyrdom videos that he watched on his phone.

His lawyers conceded that Mr. Saipov carried out the deadly attack, but they asked that the jury spare his life.

“Not because Mr. Saipov didn’t cause extraordinary harm — he did,” David E. Patton, the city’s federal public defender, said in his summation last week.

He asked the jury to make “the appropriate moral decision.”

“It is not necessary to kill Sayfullo Saipov,” Mr. Patton said. “It is not necessary to keep us or anyone else safe. It is not necessary to do justice. So we are asking you to choose hope over fear, justice over vengeance and, in the end, life over death.”

A prosecutor, Amanda Houle, told jurors that Mr. Saipov had deserved the ultimate punishment.

“Committing murder is always horrific,” she said in her summation, “but committing murder for a terrorist organization that has as a core purpose killing and terrorizing Americans makes the defendant’s crime worse.”

The attack, which occurred a little after 3 p.m., shattered the calm of a balmy Halloween Day in 2017 when the bike path was crowded with New Yorkers and tourists.

Testimony showed that Mr. Saipov, who lived in Paterson, N.J., rented a 6,000-pound Home Depot truck, drove it into Manhattan and then sped down the bike path and plowed into bicyclists, sending some riders into the air and crushing others on the ground.

He rammed one group of 10 men from Argentina, close friends who were biking in pairs, striking and killing “every single rider on the left side of the column,” another prosecutor, Alexander Li, told the jury.

The attack left a scene of mangled bicycles, truck parts and bodies scattered on the ground. Mr. Saipov then slammed into a school bus for special-needs children, seriously injuring an attendant and a 14-year-old girl. He left his truck waving paintball and pellet guns and shouting “Allahu akbar,” Arabic for “God is great.”

The terrorist attack was the deadliest in New York City since Sept. 11, 2001.

Brittany Kriegstein contributed reporting.