If President Bush decides to invade Iraq, he's unlikely to face the kind of congressional resistance his father met when he sought to drive Saddam Hussein's forces from Kuwait in 1991.
Yet lawmakers have questions. They want evidence that Iraq is developing weapons that could threaten the United States, how many soldiers might die, what the international response might be, and who would replace Saddam if he is ousted.
"I think there are a number of difficult questions that need to be asked before Congress would support a resolution of war against Iraq. I don't think it's automatic," said Sen. Chuck Hagel, R-Neb., a member of the Senate Foreign Relations Committee.
That panel will seek answers in two days of hearings this week with Iraq analysts and former U.S. government officials. No administration officials will appear, but they probably will in September, Hagel said.
More Senate and House hearings are expected after Congress' August recess.
Bush denounced Iraq during his State of the Union address in January as part of an "axis of evil," along with Iran and North Korea.
Congress' interest in Iraq has increased as Bush administration officials step up talk of ousting Saddam, accusing him of developing weapons of mass destruction that could threaten Iraq's neighbors and the United States.
Bush has already approved covert action against Saddam and directed the CIA to increase support to Iraqi opposition groups. Six Iraqi opposition leaders will come to Washington next month for talks.
On Monday, Defense Secretary Donald H. Rumsfeld said airstrikes alone won't eliminate Iraq's weapons of mass destruction. He said much of Iraq's weapons capability may be hidden underground or could be mobile.
"A biological laboratory can be on wheels in a trailer and make a lot of bad stuff, and it's moveable. And it looks like most any other trailer," he said, speaking at U.S. Joint Forces Command headquarters in Suffolk, Va.
But some military officials question whether invading Iraq is the right approach. Some say the risks to U.S. personnel are too high and current policies of enforcing a no-fly zone and economic embargo have kept Saddam's power in check.
Sen. Carl Levin, Armed Services Committee chairman, said Congress must air that debate.
"Everyone shares the goal of trying to find a way to change the regime in Iraq," said Levin, D-Mich. But he said military leaders have privately expressed concern "that the administration has not looked at the price that has to be paid in terms of the military attack."
Iraq is a delicate issue for lawmakers. They want to be able to question Iraqi policy without being seen as challenging the authority of a popular president leading the war on terrorism.
"There's no real political benefit to opposing Bush," said Michael E. O'Hanlon, a foreign policy analyst at the Brookings Institution. "If we oppose him and he does go to war, there is a definite political cost."
That lesson was learned in 1991, he said. Many in Congress -- mostly Democrats -- opposed a resolution supporting the use of force against Iraq. The House resolution passed 250-183, while the Senate voted 52-47. The war turned out to be brief, successful and popular with the American public.
Rep. Tom Lantos of California, top Democrat on the House International Relations Committee, said he is certain a vote would be different this time.
"September 11 has shattered the innocence of many members," he said. "There is now a general recognition, though not universal, that global terrorism and countries that support terrorism represent a threat to vital U.S. interests."
The administration has not said if and how it would consult with Congress if it wants to invade Iraq. White House spokesman Sean McCormack called the issue hypothetical since no invasion is imminent.
Presidents have questioned the constitutionality of the Vietnam-era War Powers Act that requires a president to get congressional approval for U.S. forces being sent into battle for more than 60 days.
But Hagel said, "I can't imagine this administration striking out unilaterally against Iraq and not coming to the Congress and wanting us to go on record in support."