WASHINGTON • Members of Congress are reacting sharply to a plan being considered by the White House to transfer abroad five of the most dangerous prisoners from Guantanamo Bay as a gesture to the Taliban in advance of Afghanistan peace talks.

It would be the first time detainees from the "too dangerous to transfer" list have been relocated outside of U.S. control. The swift opposition from leading Republicans underscored President Barack Obama's continuing difficulty to deliver on his promises to shut down the prison at the U.S. naval base in Cuba.

The Obama administration has suggested the transfer could provide a "confidence-building" measure toward peace talks with Taliban leaders as it brings the U.S.-led war in Afghanistan to a close. The Pentagon this week announced plans to turn over the lead combat role to Afghan forces next year.

Sen. John McCain of Arizona, the top Republican on the Armed Services Committee, called the proposed transfer of dangerous detainees from Guantanamo a "very, very bad idea."

"There's lots of ways you can build confidence without releasing people like that," McCain said.

The five detainees from the no-transfer list would be sent to Qatar, according to sources granted anonymity to discuss the classified information. But what would happen after they arrived there remained unclear.

With the nation's top four intelligence officers arrayed at a congressional hearing Thursday, Rep. Mike Rogers, R-Mich., said that the path the administration had taken in the negotiations with the Taliban "crosses a pretty dangerous line" in U.S. policy.

"Dealing with an organization that is in the company of known terrorists is not a good idea," Rogers, chairman of the House Intelligence Committee, said after the session.

"These are five of the meanest, nastiest killers in the world," said Sen. Saxby Chambliss of Georgia, the top Republican on the Senate Intelligence Committee. "To say that we're going to release them as a symbol of our willingness to negotiate a peace, that's terrible."

The administration did not provide names of those under consideration for transfer.

Top members of Congress were briefed on the proposal as far back as November, said a source who spoke on condition of anonymity because the briefings were classified. The National Security Council convened senior lawmakers this week, the sources said, to discuss the status of early negotiations with the Taliban, including the transfer proposal.

James Clapper, director of national intelligence, told the Senate Intelligence Committee this week that the proposal was "very, very preliminary." Publicly and privately, administration officials have been circumspect about their expectations.

The transfer could be the first of so-called high-level detainees — the five under consideration have been on a 2009 list of 48 determined by the administration to be "too dangerous to release," administration officials testified this week.