In his labored eulogy for the Baker peace mission in Geneva, Tariq Aziz offered the U.S. Congress a useful reminder of its own role, past and present, in a crisis that threatens world peace. Aziz's zinger for Capitol Hill erases any doubt that Congress should now vote to support President Bush's policies in the Persian Gulf.

Instead of trying to woo Congress, Aziz sought to intimidate and shame some of its most influential members. He dredged up the visit to Baghdad last spring by "prominent senators" led by Minority Leader Bob Dole (R-Kan.) to chat amiably with Saddam Hussein as the Iraqi dictator threatened to incinerate Israel. Saddam also had then begun the war of words with Kuwait that he shortly turned into a war of iron and blood.

Why, on the threshold of the congressional vote, did Aziz go out of his way to embarrass Dole and the others who fought the imposition of sanctions on Iraq, who excused Saddam's barbaric treatment of his own people and who went cooing into the dictator's den? The answer is both cultural and tactical, and it bears directly on how Baghdad will read this week's congressional action.

The "shame factor" is a powerful force in Arab politics. A foe or rival who can be made to feel shame is a weakened opponent. The insults and ugly names that Arab leaders hurl at each other are calculated with that effect in mind. So, no doubt, was Aziz's gimmicky rejection in Geneva of the tough letter Bush had written to Saddam. Shame on you, Georgie Bush, for using naughty words like "Kuwait" and "aggression."

In the immediate sense, Aziz misreads the utility of the shame factor in American politics. His Geneva performance has to stick in the craw of even the most dovish Democrats on the Hill. To reward the thugs of Baghdad by voting against Bush now requires a cast-iron stomach and an ability to ignore how this crisis developed in the first place.

For Aziz accurately reminds many U.S. legislators that their behavior toward Iraq during the past two years encouraged Baghdad to think that the United States would not seriously oppose Saddam's ambitions. No more than the Bush administration does Congress approach this final debate on Iraq with clean hands.

Congressional leaders joined the White House in thwarting efforts in 1988 and 1989 to warn and punish Saddam for his systematic use of poison gas by enacting economic sanctions. He repaid their courtesy with Kuwait. Relying on economic sanctions now to drive him from Kuwait is the latest example of wishful American thinking in dealing with Saddam.

The administration and Dole have at least learned from their mistakes. But this does not seem to be the case for members of Congress who distrust Bush, the Pentagon and ultimately themselves so much that they will vote to tell Saddam that America is not prepared to use force to oppose him now.

There is a shame factor at work in the Capitol Hill debate. But it has nothing to do with Iraq. It has to do with the political scars of Vietnam, which paradoxically remain more vivid than military scars a quarter-century after that conflict began.

Because of the long arm of incumbency, some of today's most influential Democratic House committee chairmen were already in Congress when the Tonkin Gulf resolution was debated in 1964, and they voted to give Lyndon Johnson blanket authority to pursue the wrong war in the wrong place at the wrong time.

They and other Democrats who saw their party ravaged by the divisions Vietnam produced instinctively shrink back from anything that smacks of a replay of that debacle. But it is possible to make the opposite choice in similar situations and be wrong twice. Those who refuse to join the president in giving a final ultimatum to Saddam because of the ghost of the Tonkin Gulf resolution and its aftermath take that risk.

Bush bears a great deal of the responsibility for the distrust he inspires among Democrats and in the population at large. He now pays the price for his ignoble presidential campaign of 1988 and the ruthless appeals to domestic partisanship still being voiced by his chief of staff, John Sununu. The president's call in his radio address last weekend for bipartisanship on foreign affairs rings hollow in these circumstances.

But this does not eclipse the reality that Saddam Hussein sent Tariq Aziz to Geneva not to seek peace but to seek an American backdown. A vote to deny Bush the authority to use force if necessary would convince Saddam he can stay in Kuwait, outlast sanctions and survive. War may have been delayed, but it will not have been avoided.

The last chance to avoid war by convincing Saddam of U.S. intentions will be lost if either house of Congress votes to return to a policy of pretending that America can again afford to ignore or accommodate Saddam Hussein's aggression.