In a day devoted entirely to the attacks, the common theme was that terrorists who crashed hijacked jets into the twin towers of the World Trade Center and into the Pentagon had committed an act of war against the United States.

When diplomacy fails, said the Senate's second-ranked Democrat, Harry Reid of Nevada, ''We must use military force in this war against terrorism.''

''We will rid this world of the stench of your existence,'' Rep. Shelley Berkley, D-Nev., said of the terrorists. ''There is no such thing as a measured response to this horrific attack. This act of war will be avenged.''

Both the House and Senate took up a resolution condemning terrorism and expressing solidarity with the president in his determination to ''punish the perpetrators of these attacks, as well as their sponsors.''

A room was set up in a House office building for lawmakers to donate blood.

Congress also broke from the business of the day to hold an evening prayer vigil for the victims of Tuesday's attacks. As the Marine Corps band played, lawmakers and their spouses filed into the Capitol Rotunda. Many later sang aloud as the band played ''God Bless America.''

''There are often times in our lives when things happen. We don't know why,'' Rep. J.C. Watts, R-Okla., told the crowd. ''We just have to call on faith and climb in God's lap and say, 'Here, Father, fix it.'''

Sen. Barbara Mikulski, D-Md., said, ''I believe God was with them in their hour of fear, travail and death. I believe he will be with us in our search for answers and justice. With God's grace, we're going to be a stronger nation.''

Lawmakers also began work on a request from President Bush for an unspecified amount of emergency funding to help victims, begin reconstruction and bolster defenses against terrorism.

On Tuesday senators and representatives were ordered out of their offices in what Capitol Police said was the first mandatory evacuation ever of the entire Capitol complex. Lawmakers were eager to get back to work Wednesday because, Senate Republican leader Trent Lott said, ''It's so important that we show that even these terrible acts cannot stop America from going forward.''

''Yesterday changed our world,'' House chaplain the Rev. Daniel P. Coughlin said in his opening prayer before an unusually well-attended session. ''Today we are changed.''

Australian Prime Minister John Howard had been scheduled to address a joint session of Congress on Wednesday. That was canceled, but Howard attended the House opening, sitting in the visitors' gallery in what House Speaker Dennis Hastert termed a show of solidarity with Americans.

Both the House and Senate broke during the day for closed-door briefings with Defense Secretary Donald Rumsfeld and other Cabinet secretaries. Congressional leaders also went to the White House to confer with the president.

Beyond the resolutions of unity, several members were proposing concrete action: Sen. Arlen Specter, R-Pa., suggested that Congress officially declare war against Osama bin Laden, the top suspect in the terrorist attacks, and his coconspirators. ''Bin Laden is at war with the United States, and it is time that we reciprocate,'' he said.

Reid recommended that Congress create an office whose head would oversee the nation's fight against terrorists. Sen. Kay Bailey Hutchison, R-Texas, said she would propose legislation to put sky marshals on random commercial aircraft.

There were voices of restraint: Rep. John Conyers, D-Mich., whose hometown of Detroit has a large Arab-American population, saw a ''real danger that this tragedy could result in prejudice, discrimination and crimes of hate against Arab-Americans and others.''

Rep. David Dreier, R-Calif., said he had a problem with a declaration of war against bin Laden while the role and involvement of the Saudi-born, Afghanistan-based militant was still unclear.

Almost all committee hearings scheduled for Wednesday were canceled. One that did go forward, in the Senate Governmental Affairs Committee, examined the terrorist threat to the nation's computer and telecommunications systems.

''If we are serious about commencing a war against terrorism,'' said Rep. Joe Lieberman, D-Conn., the panel's chairman, ''we have to understand it's going to be a different kind of war.''

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