The unusual private session was prompted by Democrats unhappy that Republicans haven't investigated intelligence used by the administration that led to the war in Iraq.
Immediately after returning to public session, Senate Intelligence Committee Chairman Pat Roberts says Republicans have "agreed to do what we agreed to do."
Democrats forced the Republican-controlled Senate into an unusual closed session Tuesday, questioning intelligence that President Bush used in the run-up to the war in Iraq and accusing Republicans of ignoring the issue.
"They have repeatedly chosen to protect the Republican administration rather than get to the bottom of what happened and why," Democratic leader Harry Reid said.
Taken by surprise, Republicans derided the move as a political stunt.
"The United States Senate has been hijacked by the Democratic leadership," said Majority Leader Bill Frist. "They have no convictions, they have no principles, they have no ideas," the Republican leader said.
In a speech on the Senate floor, Reid demanded the Senate go into closed session. The public was ordered out of the chamber, the lights were dimmed, and the doors were closed. No vote is required in such circumstances.
Reid's move shone a spotlight on the continuing controversy over intelligence that President Bush cited in the run-up to the war in Iraq. Despite prewar claims, no weapons of mass destruction have been found in Iraq, and some Democrats have accused the administration of manipulating the information that was in their possession.
CBS News correspondent Bob Fuss reports that Democrats say the indictment of Vice President Dick Cheney's chief of staff, I. Lewis "Scooter" Libby brings the issue into the forefront. Fuss reports that no one can remember the last time the Senate rule was used this way — to grab control of the Senate to discuss an issue the majority party does not want to discuss.
Libby was indicted last Friday in an investigation that touched on the war, the leak of the identity of a CIA official married to a critic of the administration's Iraq policy.
"The Libby indictment provides a window into what this is really all about, how this administration manufactured and manipulated intelligence in order to sell the war in Iraq and attempted to destroy those who dared to challenge its actions," Reid said before invoking Senate rules that led to the closed session.