Let's assume that President Bush is right to take us to war against Iraq.

For the sake of argument, let us also ignore the costs of the administration's failed diplomacy. Indeed, for now, let's hang the whole diplomatic mess on the French. And, yes, let us hope for a rapid American victory.

But before the rally-round-the-flag effect begins to quell critical commentary, let us face the great defect in the administration's call to arms. The shortage of candor about the sacrifices entailed in this bold venture helps explain why so many Americans outside the ranks of the president's most fervent supporters have found it difficult to give their wholehearted assent to the endeavor.

John F. Kennedy is legendary for declaring that the United States was willing to "pay any price, bear any burden, meet any hardship, support any friend, oppose any foe, in order to assure the survival and the success of liberty."

But what price has Bush asked of us and, in political terms, of himself? Right up to the eve of war, the answer has been: precious little.

This is the significance of the president's resolute refusal to put a price tag on this war in advance. It is a price tag that involves not only treasure but also the commitment of tens of thousands of American men and women in the military to a very hard task, likely for years to come.

But instead of following Kennedy's example by speaking of the difficulty and expense of his course, the president and his lieutenants have tried to play down the potential costs, or have simply feigned ignorance.

Asked by Tim Russert on "Meet the Press" whether the war might cost $100 billion, Vice President Cheney wouldn't discuss the potential burden. "I can't say that, Tim," Cheney said. "There are estimates out there." Note the denial of responsibility in that phrase "out there," as if the administration had no estimates of its own.

Russert also asked whether "we would have to have several hundred thousand troops there" in Iraq "for several years in order to maintain stability." Cheney replied: "I disagree." The vice president wouldn't say how many troops we would need but said that "to suggest that we need several hundred thousand troops there after military operations cease, after the conflict ends, I don't think is accurate." In other words: Don't worry about it.

The reluctance to challenge Americans extends to domestic policy. In the run-up to war, the president is telling his wealthiest supporters to party on. How else is one to interpret his call for the repeal of taxes on dividends? The administration says the measure would stimulate the economy, though even supporters of the idea have acknowledged it would do little to give the economy a short-term jolt.

Fortunately, these tax cuts are too much even for some in the president's own party. A group of 11 moderate House Republicans -- among them Mike Castle of Delaware, Amo Houghton of New York, Fred Upton of Michigan and Ray LaHood of Illinois -- wrote their leadership last week declaring their opposition to $1.4 trillion in tax cuts.

"The war against terror and the crisis in the Gulf are of key concern to the American people," they said. "However, meeting these challenges should not cause us to abandon our party's commitment to fiscal responsibility. . . . We must pursue a budget policy that fairly limits both spending and tax reductions to those that are absolutely needed at this time."

In a time of war, it should not fall to this honorable handful of House members to state the obvious. A government proposing revolutionary departures in foreign policy should not pretend that its objectives can be pursued painlessly and with no disturbance to its domestic objectives.

Supporters of going to war have regularly chastised their opponents for refusing to face the reality of Saddam Hussein's threat and the need for radical measures to eliminate it.

Now it is their turn to face reality. From a desire not to unsettle the delicate foundations of their political coalition, supporters of a grand new American role in reordering the world have held their tongues about the cost of their enterprise. They have not said what price or burden or hardship they are asking of their fellow Americans, especially of their own supporters. Perhaps Bush will lead by breaking the silence and ask more of us -- and of himself. Rallying a nation to war demands sacrifices of everyone, including the president of the United States.