Washington ? Vice President Dick Cheney warned Monday that the United States could face devastating consequences from any delay in acting to remove Saddam Hussein as president of Iraq.

Lawmakers urged President Bush to get their support before any invasion, even though White House advisers say congressional assent is not legally required.

Cheney’s remarks were among the strongest by a high administration official about the urgency of ousting Saddam, spoken even as the White House contends no decision has been made to invade Iraq.

Speaking at a Veterans of Foreign Wars convention in Nashville, Tenn., Cheney dismissed what he called “deeply flawed” logic of people who argue against a pre-emptive strike to stop Saddam from developing chemical, biological or nuclear weapons.

“What we must not do in the face of a mortal threat is to give in to wishful thinking or willful blindness,” he said. “We will not simply look away, hope for the best and leave the matter for some future administration to resolve.”

Cheney pressed the administration’s case for invading Iraq amid growing misgivings about the potential loss of lives, the cost to U.S. taxpayers, the effects on other countries friend and foe and uncertainty about who would replace Saddam and how long the U.S. commitment would last. Many of the admonitions for caution have come from Republican lawmakers and officials of former GOP administrations.

“If this is a noble cause, and it’s in the interest of our country, then the president needs to make the case,” said Sen. Chuck Hagel, R-Neb., a member on the Senate Foreign Relations Committee.

He said Bush should seek Congress’ backing before ordering an invasion of Iraq, regardless of whether it’s required.

“If the president is going to commit this nation to war,” Hagel said, “he’d better have the support of the Congress and the American people with him.”

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

Gephardt spoke during a campaign appearance in Waterbury, Conn., on behalf of U.S. Rep. Jim Maloney, D-Conn.

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.

In Crawford, Tex., where Bush is vacationing, White House spokesman Ari Fleischer said White House counsel Al Gonzales advised Bush he did not need congressional authority to go to war with Iraq. Nevertheless, Fleischer said: “The president will consult with the Congress, because Congress has an important role to play.”

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

“Congress ultimately controls the government’s budget, and the president should seek the active involvement of Congress in developing his policy.”

In his Tennessee speech, Cheney delivered perhaps the administration’s most comprehensive argument to date for ousting Saddam, although Bush and his advisers already had made most of the points he offered.

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

Those who say Iraq should be attacked only if Saddam develops a nuclear weapon later would 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,” he said.

The comments reflect 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 just begun exploring whether the United States should attack Iraq. The Senate Foreign Relations Committee held two days of hearings before the August break, and more hearings are expected in the fall in the House and Senate.

Lawmakers have circulated letters and offered resolutions calling on Bush to seek congressional authorization before attacking Iraq.

If invoked, the War Powers Act, passed in 1973 late in the Vietnam War, would prohibit the president from waging war for more than 60 days without congressional approval or a declaration of war by Congress.