The Senate Intelligence Committee voted Thursday to make public a long-awaited report that concludes that the CIA’s use of brutal interrogation measures did not produce valuable intelligence and that the agency repeatedly misled government officials about the severity and success of the program.

The decision, opposed by three Republicans on the panel, means that the findings will be sent to the White House and the CIA, putting the agency in the awkward position of having to declassify a document that delivers a scathing verdict on one of the most controversial periods in its history.

“The purpose of this review was to uncover the facts behind this secret program, and the results were shocking,” Sen. Dianne Feinstein (D-Calif.), the committee’s chairman, said in a statement Thursday. “The report exposes brutality that stands in stark contrast to our values as a nation. It chronicles a stain on our history that must never again be allowed to happen.”

U.S. officials said it could be months before the executive summary of the panel’s inquiry is released to the public. But Thursday’s vote marked the formal end of a four-year Senate investigation of the CIA’s use of waterboarding and other harsh tactics against terrorism suspects in the aftermath of the Sept. 11, 2001, attacks.

President Obama has signaled his support for the public release of the findings and an executive summary, a 481-page section at the front of a classified report that in its complete form runs to more than 6,200 pages and includes detailed accounts of the CIA’s treatment of dozens of detainees.

The agency will work “expeditiously” to declassify the document, CIA spokesman Dean Boyd said. He said the agency has acknowledged the “shortcomings” of the interrogation program. “At the same time,” he added, “we owe it to the men and women directed to carry out this program to try and ensure that any historical account of it is accurate.”

The report’s arrival at agency headquarters creates a significant dilemma for CIA Director John Brennan, who must determine how far to go in defending the agency without further damaging his relationship with Congress.

Any suspense over the committee vote ended earlier this week, when Maine’s two senators on the intelligence panel — Republican Susan Collins and independent Angus King — signaled that they would side with Democrats and vote in favor of declassification.

In an interview, King said the document convinced him that what the CIA had done was torture. “I don’t have any doubts on that fact,” he said. “It’s a pretty hard read. It’s very disappointing.”

The report, based on a review of millions of internal CIA records, found scant evidence that the use of “enhanced” interrogation techniques generated meaningful intelligence. It accuses agency officials of overstating the significance of alleged terrorist plots and prisoners, and exaggerating the effectiveness of the program by claiming credit for information detainees surrendered before they were subjected to duress.

For years, the agency made inaccurate statements to the president, the National Security Council and Congress, King said. “That’s one of the most disturbing parts of this — the institutional failure.”

Many Republicans and former CIA officials dispute those broad conclusions.

At least six Republicans on the committee, including ranking Republican Saxby Chambliss (Ga.), were expected to submit dissenting views that raised objections to its findings and methodology, according to a progress report on the investigation included in a recent intelligence spending bill.

Chambliss said he thought the program provided valuable intelligence and called the committee’s inquiry a “waste of time.” Still, he said, the public has a right to see the summary and minority views. “We need to get this behind us,” he said.

The report was assembled entirely by Democrats. Republicans abandoned the investigation shortly after it began in 2009, citing concerns that it would be shaped by political considerations as well as plans not to interview CIA officials who were being scrutinized.

The agency submitted a long response last year to an earlier draft of the Senate report that officials said identified numerous errors and contested many of the committee’s conclusions. Current and former CIA officials said the agency is weighing whether to update that response and release it to the public with the Senate report.

A former CIA official said there is an expectation among many inside the agency that Brennan will issue “a competing assessment” that critiques the committee’s findings. “There are a lot of people who worked for this program for years in good faith who still believe that it was effective,” the former official said.

But others warned that staunchly defending a program that Obama described as torture and dismantled four years ago carries political risks for the CIA.

If Brennan goes too far in rejecting the Senate report, “he’ll have torn his relationship with the oversight committees and he won’t get very many brownie points in the high regions of this government,” said Fred Hitz, a former CIA inspector general. “He may make a certain hard core of agency employees feel that he’s standing behind them, but there’s more at stake here.”

Although a fierce critic of the CIA’s interrogation program, Feinstein has been an ally to the agency on other fronts. She is such an ardent defender of its armed drone operations, for example, that she has fought against the Obama administration’s efforts to shift the authority for lethal drone operations to the Defense Department.