WASHINGTON — Obama administration officials told lawmakers that Sgt. Bowe Bergdahl’s life could have been in danger if details about a covert operation to swap him for five Taliban detainees had been divulged, a senior administration official said Thursday.

The disclosure came as the administration sought to tamp down bipartisan anger in Congress over its decision to conduct the prisoner exchange without first notifying lawmakers, as required by federal law.

“The senators were told, separate and apart from Sgt. Bergdahl’s apparent deterioration in health, that we had both specific and general indications that Sgt Bergdahl’s recovery — and potentially his life — could be jeopardized if the detainee exchange proceedings were disclosed or derailed,” the official said in a statement.

Administration officials earlier had cited concerns about Bergdahl’s declining health, and the conflicting narrative provided at a closed-door briefing Wednesday night for all 100 senators raised more questions among some members of Congress.

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“Remember what they said in the first place: They were doing this because of health reasons,” said Sen. James Risch, R-Idaho. “Now they’re backing away from that and they’ve got a new reason. That would cause one to question whether or not that is a legitimate claim or not.”

The administration official, speaking on condition of anonymity, said Bergdahl’s health after five years in captivity was a factor in the deliberations. “Our judgment was that every day Sgt. Bergdahl was a prisoner his life was at risk, and in the video we received in January, he did not look well,” the senior administration official said. “This led to an even greater sense of urgency in pursuing his recovery.”

Sen. Chuck Grassley, R-Iowa, called on the administration to release the legal analysis for not notifying Congress within 30 days of transferring the detainees, saying “the possible return of these individuals to the battlefield is a matter of high interest to members of our military and the American people.”

Some Democrats, including Alaska Sen. Mark Begich, said they believed the administration moved as it saw necessary. “I think timing was everything, and I think it was important to get him out of there,” Begich said.

From Brussels, where he was meeting with European leaders, President Obama said he’d make “absolutely no apologies” for seeing that a U.S. service member was returned to the United States.

The president made no mention of a threat to Bergdahl’s life but repeated concerns about his health, saying: “We had a prisoner of war whose health had deteriorated and we were deeply concerned about, and we saw an opportunity and we seized it. And I make no apologies for that.”

Obama said the administration had briefed Congress earlier on similar deals to free Bergdahl and contends that it is not bound by the requirement that it notify Congress if it plans to transfer Guantánamo detainees.

“Because of the nature of the folks that we were dealing with and the fragile nature of these negotiations, we felt it was important to go ahead and do what we did,” he said.

Obama’s remarks came as Pentagon officials said Bergdahl was continuing to recover at an Army medical facility in Landstuhl, Germany.