CNN — 

President Joe Biden announced Monday that he is taking 37 people off federal death row to serve out life sentences behind bars — a decision that leaves only three federal prisoners awaiting execution when President-elect Donald Trump takes office next month.

“Today, I am commuting the sentences of 37 of the 40 individuals on federal death row to life sentences without the possibility of parole,” Biden announced in a statement released Monday.

Notably, the president did not commute the sentences of three people whose crimes included mass shootings or acts of terrorism: Dzhokhar Tsarnaev, one of two brothers responsible for the deadly Boston Marathon bombing in 2013; Dylann Roof, a White nationalist who massacred nine people at a historically Black church in Charleston, South Carolina, in 2015; and Robert Bowers, who killed 11 worshippers at Pittsburgh’s Tree of Life Synagogue in 2018.

“These commutations are consistent with the moratorium my Administration has imposed on federal executions, in cases other than terrorism and hate-motivated mass murder,” Biden said, referring to his Justice Department’s halt on federal executions.

The majority of the 37 individuals whose sentences were commuted Monday were convicted for less high-profile offenses, such as murders tied to drug trafficking or the killings of prison guards or other inmates.

“Make no mistake: I condemn these murderers, grieve for the victims of their despicable acts, and ache for all the families who have suffered unimaginable and irreparable loss,” Biden said in his statement. “But guided by my conscience and my experience as a public defender, chairman of the Senate Judiciary Committee, Vice President, and now President, I am more convinced than ever that we must stop the use of the death penalty at the federal level. In good conscience, I cannot stand back and let a new administration resume executions that I halted.”

The move comes as opponents of the death penalty are bracing for Trump’s return to the White House. During the 2024 campaign, Trump indicated he would restart federal executions and work to expand the pool of crimes eligible for capital punishment under federal law, which generally allows for the death penalty in cases of murder, espionage and treason.

Biden’s announcement also comes after he pardoned his son Hunter Biden this month for federal tax and gun convictions and as the White House has said that further clemency and commutation announcements were forthcoming. President Biden this month also granted clemency to roughly 1,500 people in the biggest single-day act of clemency in modern history.

Opponents of capital punishment and top Biden allies such as Sen. Chris Coons had been encouraging the president to consider commuting federal death penalty sentences.

“President Biden has an opportunity to make history by addressing the racist and unjust federal death penalty system and keep an early campaign promise he made to the American people,” Anthony Romero, executive director of the American Civil Liberties Union, said this month after the ACLU and more than 130 other civil and human rights organizations sent Biden a letter urging him to commute the sentences of those on death row.

Coons, a Delaware Democrat, told CNN’s Dana Bash on Sunday that Biden should consider the commutations on a “case-by-case basis.”

“There are some real questions about the fairness and the process of the death penalty in the United States. And I don’t know what President Biden will ultimately do, but I think there are reasons — both in terms of racial justice, due process and what it says domestically and to the world about our values, if we were to go ahead and execute all of these individuals rather than have them spend the rest of life in prison,” Coons said on “State of the Union.”

Biden campaigned in 2020 on abolishing the federal death penalty, and early in his presidency imposed a moratorium on federal executions while the Justice Department reviewed the practice. Biden’s attorney general, Merrick Garland, has not sought the death penalty in any new cases, although the Justice Department continued to back death sentences for some federal defendants, including Tsarnaev and Roof.

Outside of the federal system, there are over 2,000 people in the United States who were convicted in state courts and put on death row, according to the Death Penalty Information Center. Biden has no power to stop those death sentences.

Opponents fear Trump’s return to the White House will herald a new round of federal executions in an echo of the final months of the president-elect’s first administration. Thirteen people were executed in the last seven months of Trump’s first term after then-Attorney General Bill Barr revived the practice from a 17-year hiatus.

Trump has voiced support for imposing the death penalty on convicted human traffickers and drug dealers, while also saying he would seek to have prosecutors pursue the death penalty for migrants who kill American citizens or anyone who kills a law enforcement officer.

While the Justice Department under Trump could resume seeking the death penalty in future cases, it cannot undo any commutations that Biden has issued.

CNN’s Dakin Andone contributed to this report.