W By Dana Milbank

ASHINGTON – The White House billed Monday night’s speech by President Bush as a chance for him to explain to average Americans why it is necessary to disarm and replace Iraqi President Saddam Hussein. The speech didn’t come a moment too soon.

Even as Bush in recent days has become assured of lopsided votes in Congress that would authorize military action, a series of opinion polls have indicated that the public’s enthusiasm for such action is tepid and declining. Americans remain unsure of the threat Saddam poses and unconvinced about the best method to deal with that threat.

Monday night, Bush acknowledged the many doubts Americans have about a confrontation with Iraq, and he offered a lawyerly refutation of those doubts. “Many Americans have raised legitimate questions,” Bush said. “About the nature of the threat. About the urgency of action–and why be concerned now?”

As expected, Bush offered little new information Monday night, other than to disclose that Iraq has a growing number of aircraft that could deliver chemical and biological weapons, possibly even to target the United States.

Rather, his address had elements that ranged from frightening (“it could have a nuclear weapon in less than a year”) to reassuring (“we will act with allies at our side”) to belligerent (“Saddam Hussein is a homicidal dictator who is addicted to weapons of mass destruction”) to sobering (“military conflict could be difficult”). Its effect was to amass evidence–much of it inconclusive in the eyes of security experts–that painted Iraq as a clear and present danger to the United States and a firm ally of al-Qaida.

Just as Bush did at the United Nations a month ago, when he presented himself as the champion of multilateral action and not its foe, he sought Monday night to turn arguments against him upside down. To those raising doubts that Bush is leading the nation on a dangerous and ill-conceived military adventure, Bush argued that he is the one pursuing the safest approach. “There is no easy or risk-free course of action,” he said. “Some have argued that we should wait, and that is an option. In my view, it is the riskiest of all options.”

White House officials had grown concerned that public support for using force against Saddam has softened despite Bush’s growing support in Congress. A Gallup poll released Monday found a bare majority of Americans–53 percent–favored a ground invasion of Iraq, down from 61 percent in June and 74 percent last November. An ABC News poll, also released Monday, found that 50 percent of Americans agreed with the proposition that diplomacy does not work with Iraq and the time for military action is near; 44 percent favored holding off on military action and pursuing diplomacy.

The divergence in views between ordinary Americans and their elected representatives indicates the administration has done an uneven sales job–and one that Bush aides said Monday night’s address was meant to remedy. “They really haven’t made an attempt yet to explain to the American people in real terms the necessity of the action,” said John Weaver, an adviser to several Democratic congressional candidates.

Bush aides interpret the soft poll numbers to mean that Americans are giving Bush the benefit of the doubt but are not convinced about the merits of his argument.

In the short term, such ambivalence is not a problem. History has shown that as soon as the United States launches a military action, a surge in public support is a virtual certainty. But the soft support presents a potential problem for the long term. If Americans have doubts about the rationale for the action in the first place, their support could fade if the conflict in Iraq becomes bloody and extended.

With such concerns in mind, the administration set out Monday night to convey more comprehensively and methodically its rationales for war. The arguments were not new, but the packaging was. Bush eschewed most of the Iraq applause lines he shouts from the campaign stump. Instead, he spoke soberly in front of a world map in the Cincinnati Museum Center, the United States behind his right shoulder and the Persian Gulf behind his left.

The White House selected the location for the speech–Ohio–because there were no competitive races in the area that would make Bush appear to be playing politics with the war. And, to make the threat more vivid, Bush aides decided to declassify for the speech a series of before-and-after photos of Saddam’s weapons facilities.

To those who wonder why Iraq represented a unique threat, Bush said: “Because it gathers the most serious dangers our age in one place.” To those who argued that Iraq would distract America from the war on terrorism, Bush replied that “confronting the threat posed by Iraq is crucial to winning the war on terror.” To those who wondered how far Saddam is from acquiring the bomb, he answered: “Well, we don’t know exactly, and that is the problem.”

Bush labored to link Iraq to al-Qaida, even mentioning an unnamed terrorist leader allegedly associated with chemical and biological attacks who was given medical treatment this year in Baghdad. But while the ties between Iraq and al- Qaida are hotly disputed, Bush ultimately linked the two by pointing to the new sense of vulnerability Americans acquired on Sept. 11, 2001–stating that Iraq could threaten Americans on their own soil.

“We resolved then, and we are resolved today, to confront every threat, from any source, that could bring sudden terror and suffering to America,” he said.