Determined to show a united front, Congress moved with uncommon speed Thursday toward approving $40 billion to combat terrorism and recover from attacks on the World Trade Center and the Pentagon.

Lawmakers also labored over a second measure authorizing the president to use "necessary and appropriate force" in retaliating for the terrorist strikes. But some were balking at the White House's request for blanket support for the use of force to "deter and pre-empt any related future acts of terrorism or aggression against the United States."

Even so, the emergency spending measure was being written in an extraordinary display of speed and bipartisan unity.

"We are shoulder to shoulder. We are in complete agreement that we will act together as one," said House Democratic Leader Dick Gephardt of Missouri.

Speaker Dennis Hastert, R-Ill., said Bush agreed to sign a bill with double the $20 billion he requested earlier Thursday after meeting at the White House with New York lawmakers. Congress hoped to approve the package by week's end.

"There is a unanimous understanding that whatever we do this week is a very minimal down payment to what will be required and what we will do in the days and weeks ahead," said Senate Majority Leader Tom Daschle, D-S.D.

The agreement was worked out late in the afternoon, minutes before the Capitol was evacuated for about a half hour because of a suspicious package.

Lawmakers from New York -- where the brunt of the casualties and damage occurred when the World Trade Center was obliterated -- said they got a commitment Thursday from Bush for $20 billion to aid the state's recovery.

In a day marked by several bipartisan meetings -- unusual in themselves -- Democratic and Republican leaders traveled together across the Potomac River to view rescue and recovery efforts at the Pentagon.

Under the broad proposal, the money would go to attack victims; costs by the federal and local governments for the rescue, cleanup and rebuilding efforts; and improved security for transportation systems.

It could also be used "to counter, investigate or prosecute domestic or international terrorism" and for "supporting national security" -- which could give Bush wide leeway to use the funds to strike back at terrorists and their supporters.

Both parties also seemed eager to approve separate legislation endorsing a presidential use of force against those responsible for the attacks.

"It is always wiser to demonstrate national unity" by showing Congress supports such action, said Senate Foreign Relations Committee Chairman Joseph Biden, D-Del.

Participants said completion of that bill could slip to next week, complicated by the age-old jealously between the two branches of government over the power to wage war. One of the stickiest points was proposed White House language putting Congress on record behind a Bush use of force in response to the attacks and any future incidents, said aides from both parties who spoke on condition of anonymity.

"We are a coequal branch of government, and we need to ... make sure that we've thought it through carefully," said Senate Minority Leader Trent Lott, R-Miss.

In 1964, Congress approved the Gulf of Tonkin resolution authorizing President Johnson "to take all necessary measures" to protect U.S. forces and prevent aggression. Johnson and subsequent presidents used that resolution to wage the Vietnam War, to the subsequent regret of many lawmakers.

The Constitution gives the president, as commander in chief, authority to wage war while leaving Congress the power to declare war. Lawmakers of both parties widely support empowering the president to retaliate against the terrorists, but are leery of giving Bush open-ended power.

Rep. Bob Barr, R-Ga., was among lawmakers favoring a declaration of war against terrorists and their sponsors. He said it would show how seriously the United States viewed the attacks.

But few leaders seemed to share that view. Sen. John Warner of Virginia, top Republican on the Senate Armed Services Committee, said that would be "beneath our dignity."

Bush formally requested the $20 billion earlier Thursday -- roughly one-third of what it cost for the 1991 Persian Gulf War, and about what Congress provided for the Justice Department this year.

"Our first priority is to respond swiftly and surely," Bush wrote to congressional leaders. "We need to do so in a way that will make Americans proud, especially those heroes who are struggling so valiantly" with the tragedy.