How come President Bush recently abandoned the administration’s line that Saddam Hussein was partly responsible for the terrorist attacks of Sept. 11, 2001?

The reversal came in a White House effort to clarify a statement by Vice President Dick Cheney the day before. Mr. Cheney had been asked, on the NBC News program “Meet the Press,” about polls showing that nearly 70 percent of Americans believe that Saddam was involved in the attacks. Did the connection exist? “We don’t know,” Mr. Cheney replied. He went on to describe alleged connections between Saddam and al-Qaida, the terrorist network responsible for the attacks.

When a reporter asked the president about Mr. Cheney’s statement, Mr. Bush said, “No, we’ve had no evidence that Saddam Hussein was involved with September the 11th.” He added some details about tenuous relationships between Saddam and al-Qaida and said, “there’s no question that Saddam Hussein had al-Qaida ties.” This link, or the lack of it, will become more important now that a draft report on weapons of mass destruction suggests that these weapons have yet to be found.

While the White House never has charged that Saddam was part of the Sept. 11 plot, the Defense Department has tried ever since to find a connection. And continual reference to a Saddam-al Qaida connection by administration officials helped persuade many Americans that Saddam was involved. The 9-11 attacks were so traumatic that this false belief was a mainstay in building support for the Iraqi campaign.

Now that Mr. Bush’s re-election race is approaching and public support for the war has slipped a bit, Democrats are increasingly questioning its justification. Sen. Edward Kennedy, D-Mass., one of the most outspoken, has called the war a fraud, which overstates the situation, but his colleagues are properly asking whether the information they were given by the White House in the months leading to the war was accurate.

It’s a fair guess that the White House chose to straighten out a widespread misconception rather than have to cope with campaign charges of misrepresentation. Such frankness is admirable as well as politically wise. The administration might consider clearing up some other misconceptions. For starters, it should re-examine the assertion that large stocks of chemical and biological weapons in Iraq could be used imminently and that a nuclear-weapons program there was close to its goal.