ASHINGTON, Sept. 13 — The Bush administration today singled out Osama bin Laden, the Islamic militant who operates from Afghanistan, as a prime suspect in Tuesday's catastrophic terror attacks and vowed a comprehensive military campaign to demolish terrorist networks and topple regimes that harbor them.

"It's not just simply a matter of capturing people and holding them accountable," said Paul D. Wolfowitz, the deputy secretary of defense, "but removing the sanctuaries, removing the support systems, ending states who sponsor terrorism."

Late today, Secretary of Defense Donald H. Rumsfeld recommended calling up members of the reserve, initially to help support the combat air patrols securing the skies over major American cities, Pentagon officials said.

Congress, despite some misgivings from lawmakers over granting President Bush open-ended authority, moved to give the administration $40 billion to wage its antiterror initiative.

As emergency workers pursued their solemn mission to find thousands of people missing in the rubble of the World Trade Center in New York and at the Pentagon, the nation remained palpably on edge. Bomb scares and suspicious packages caused the evacuation of the Capitol and buildings in Manhattan. Vice President Dick Cheney was moved to Camp David for security reasons. The armed cordon around the White House was expanded, and patrolled by police officers in full riot gear.

The administration took a more aggressive posture today after the shock of the previous two days, making Mr. Bush more visible.

"Make no mistake about it, this nation is sad," Mr. Bush said in an appearance in the Oval Office this morning. "But we're also tough and resolute, and now's an opportunity to do generations a favor by coming together and whipping terrorism, hunting it down, binding it and holding them accountable."

The president told Mayor Rudolph W. Giuliani in a telephone call this morning that he would visit New York on Friday, after leading a prayer service at the National Cathedral in Washington. He visited a Washington hospital today to offer comfort to some of those who were wounded in the attack on the Pentagon.

Secretary of State Colin L. Powell stated in the strongest terms yet that the administration believed that Mr. bin Laden was behind Tuesday's devastating attacks.

Referring to Pakistan, one of the few countries that recognizes the Islamic Taliban who rule Afghanistan, and to Afghanistan itself, Secretary Powell said, "When you look at the list of candidates, one resides in that region." Asked if that candidate was Mr. bin Laden, he replied with a curt "Yes."

He said the administration would present a case to the world against those believed responsible for the carnage in New York and Washington. "We will go after that group, that network, and those who have harbored, supported and aided that network, to rip the network up," he said.

As he mapped the start of the antiterror effort, Secretary Powell stepped up the pressure on Pakistan to help the United States bring the accused terrorist to justice. He telephoned Pakistan's leader, Gen. Pervez Musharraf, to present him with a list of actions the administration would like him to take.

Senator Joseph R. Biden, chairman of the Senate Foreign Relations Committee, met with General Mahmoud Ahmad, the head of Pakistan's intelligence services, who, according to Mr. Biden, pledged Pakistan's cooperation.

Another top national security adviser said later in the day that the attacks could have been the work of a number of linked organizations.

"We don't want to be premature," the official said. "We want to be sure we understand all the connections, not just one connection."

Mr. Wolfowitz said the United States and its allies would wage "a campaign, not a single action" to dismantle the terrorist group or groups responsible for this week's attacks, and to bring down the governments that support them.

The administration had asked Congress for an immediate $20 billion to begin building the military and intelligence force required to start the antiterror campaign.

"Twenty billion dollars is a lot of money," Mr. Wolfowitz said, "but for this country, it is a down payment on what we're going to do."

Congress is moving swiftly to approve the funds, although some lawmakers, citing the 1964 Gulf of Tonkin resolution and other earlier blank checks written to presidents to conduct undeclared wars, expressed uneasiness about Congress's so quickly ceding its constitutional powers to declare war and control the national treasury.

"We want constitutional involvement in the process in which decisions are made," said Representative David R. Obey of Wisconsin, a 32-year veteran of Congress who is the senior Democrat on the Appropriations Committee.

Mr. Bush, facing a stern test that will recast and define his tenure in office, said the campaign against terror "is now the focus of my presidency."

He said he would not neglect domestic concerns. "But now that war has been declared on us, we will lead the world to victory, to victory," he said.

The nascent campaign is being waged on a broad diplomatic front. The administration continued today to try to galvanize an international coalition, its diplomatic and military strategy focused on trying to use Russia and Pakistan in an encircling movement on the north and south of Afghanistan.

Russia has bases in the former Soviet republics of Tajikistan and Uzbekistan and could offer other assets, including intelligence, to the United States for a military assault on Mr. bin Laden in Afghanistan.

The planning and the language used by administration officials was read by military analysts as a sign that Secretary Powell, a former chairman of the Joint Chiefs of Staff, is preparing the way for a military force that could ultimately be used to occupy Kabul, the Afghan capital, and overthrow the ruling Taliban.

The Soviet Union occupied Afghanistan from 1979 to 1989, while the United States fought a proxy war, using mujahedeen rebels against the Soviet troops, who began to withdraw in 1988.

Now, Russia and the United States appeared to be looking for ways to work together against Mr. bin Laden in Afghanistan.

The deputy secretary of state, Richard L. Armitage, accompanied by a team of Pentagon and National Security Council officials, is scheduled to meet in Moscow next week with the Russian first deputy foreign minister, Vyacheslav Trubnikov. Mr. Armitage will be asking the Russians for their detailed knowledge of Afghanistan as well as for access to the Russian military facilities in Tajikistan and Uzbekistan, administration officials said.

In addition to Russian air bases in those two Central Asian nations, a crack Russian division, the 201st Motorized, operates on the border of Tajikistan and Afghanistan, officials said.

"I'm sure they will be helpful on many things," Secretary Powell said of the Russians. "They do have a great deal of experience in Afghanistan, and we will draw on all of that experience."

He acknowledged that terrorist groups were much harder to find and destroy than conventional states and their armies.

"The kind of organizations that conduct these terrorist activities make for difficult targets," the secretary said. "It is not as if you're going after an army in the field or you're trying to destroy cities or fixed installations. They're also a thinking enemy."

And he said that despite the current efforts to fashion an international alliance to conduct the battle he envisions, the United States reserves the right to act alone to protect its citizens and its interests.

"We will not be constrained by the fact that we are working with others as well," Secretary Powell said.