Legal questions aside, lawmakers say President Bush needs to seek Congress' approval before sending American troops to attack Iraq because it's the right thing to do. Vice President Dick Cheney warned of grave consequences from not acting quickly against Saddam Hussein.

"I don't play this game so much on what's legal and what's not legal," Sen. Chuck Hagel, R-Neb., said of a U.S. attack on Iraq. "If the president is going to commit this nation to war, he'd better have the support of the Congress and the American people with him."

White House counsel Al Gonzales told Bush this month that he doesn't need explicit authority from Congress to wage war with Iraq, presidential spokesman Ari Fleischer told reporters Monday in Crawford, Texas, where Bush is vacationing.

Despite that opinion, Bush has not ruled out seeking lawmakers' approval if he decides to attack Iraq, Fleischer said.

"The president will consult with the Congress because Congress has an important role to play," he said.

Bush has called for Iraqi president Saddam Hussein to be toppled, saying his development of chemical, biological and nuclear weapons threatens the United States and the world in general. Even as administration officials stress that no decision has been made to invade Iraq, they have been stepping up talk about why such an attack is needed.

Cheney, speaking at a Veterans of Foreign Wars convention in Nashville, Tenn., dismissed as "deeply flawed" the logic of those who argue against a pre-emptive strike on Saddam.

"What we must not do in the face of a mortal threat is to give in to wishful thinking or willful blindness," he said.

Those who say Iraq should be attacked only if Saddam develops a nuclear weapon would later argue "we cannot because he has a nuclear weapon," Cheney said. That would lead to "a course of inaction that itself could have devastating consequences for many countries, including our own."

Cheney pressed the administration's case for invading Iraq in the face of growing concerns about the potential loss of lives, the costs to U.S. taxpayers, the effects on other countries and uncertainty about who would replace Saddam.

Cheney delivered perhaps the administration's most comprehensive argument to date for ousting Saddam.

Failing to attack now will only allow Iraq to grow stronger, Cheney said. Forcing Saddam from power would bring freedom to Iraq, bring peace to the region, boost Arab moderates, cause extremists to rethink violence and help the Israeli-Palestinian peace process.

The point-by-point argument reflects growing unease within the White House: Aides acknowledge that Bush's critics are getting the upper hand because he can't make his case for ousting Saddam until he decides when and how to do it.

Congress has begun exploring whether the United States should attack Iraq. The Senate Foreign Relations Committee held two days of hearings right before the August break and more hearings are expected in both the House and Senate in the fall.

Under the Vietnam-era War Powers Act, the president is required to get congressional approval for introducing U.S. forces into hostilities for more than 60 days. Presidents of both parties have considered the act unconstitutional and ignored it.

Regardless of the act's legality, lawmakers say they want Bush to seek congressional authorization for an invasion.

"The president has to get congressional approval," said House Democratic leader Dick Gephardt of Missouri, speaking in Waterbury, Conn. "He must have a debate on this issue and a vote in the Congress."

Sen. Patrick Leahy, D-Vt., said the decision of going to war "should not be treated like a technicality."

"For the good of the country and for the long-term success of whatever approach we take, President Bush should follow his father's lead and support a vigorous and constructive debate on Iraq," he said, through a spokesman. Bush's father sought and received congressional backing before the 1991 Persian Gulf War.

The Republican chairman of the House International Relations Committee, Rep. Henry Hyde of Illinois, said he agreed with Gonzales, the White House counsel.

"But I also believe that any policy undertaken by the president without a popular mandate from Congress risks its long-term success," he said in a statement.