CIA Director George Tenet told lawmakers Tuesday that Iraqi President Saddam Hussein, if provoked by fears of an imminent U.S.-led attack, might assist Islamic extremists in launching an attack against the United States with weapons of mass destruction.

Saddam might see it as "his last chance to exact vengeance by taking a large number of victims with him," Tenet wrote in a letter.

Tenet's assessment came as both the House and Senate debated a resolution to authorize President Bush to use force against Iraq and followed Bush's assertion that the Iraqi leader might be planning a chemical or biological attack on U.S. interests.

It is unlikely that such an attack by Saddam would come unless he felt cornered, Tenet's letter suggested.

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Still, Tenet wrote, "Iraq's increasing support to extremist Palestinians, coupled with growing indications of a relationship with Al Qaeda, suggest that Baghdad's links to terrorists will increase, even absent U.S. military action."

Bush's drive to win war authority, meanwhile, hit a snag in the Senate.

Sen. Robert Byrd, D-W.Va., a fierce opponent of the president's Iraq war resolution, was using parliamentary tactics to delay the measure. Senate Majority Leader Tom Daschle, D-S.D., said that could easily put off a final vote until next week.

However, eventual approval of the administration-backed resolution appeared likely, and it was gaining broad bipartisan support in both chambers.

Both the House and the Senate worked into the evening on the measure and a final House vote was expected by late Thursday.

Secretary of State Colin Powell made appearances on both sides of Capitol Hill to urge lawmakers to pass the resolution with large bipartisan margins and without amendments.

"I think the resolution is timely, and we need it now," Powell told reporters. He said it would help strengthen his hand at the U.N. Security Council.

Meanwhile, Bush continued to try to drum up U.S. and international support for his hardline policies. He told a Tennessee audience that "the full force and fury of the United States military will be unleashed" should he decide to use force against Iraq. "And make no mistake about it, we will prevail," Bush added.

The night before, in a speech to the nation from Cincinnati, Bush warned that Saddam might attempt "cruel and desperate measures," including using chemical and biological weapons against U.S. forces or his own people.

But Tenet, in the letter read before a joint hearing of the House and Senate intelligence committees, suggested Baghdad "for now appears to be drawing a line short of conducting terrorist attacks with conventional or chemical or biological weapons."

Should Saddam conclude that a U.S.-led attack against his country could not be deterred, "he probably would become much less constrained in adopting terrorist action," said Tenet.

Tenet also briefed Senate members privately. And, Tuesday night, the Senate Intelligence Committee released the full text of Tenet's letter.

In the letter, Tenet said that the likelihood of Saddam's using chemical, biological or nuclear weapons "grows as his arsenal builds."

The Bush administration contends that going after Saddam is necessary because he has the capability to use weapons of mass destruction and is trying to expand it. The administration also stresses that he has used them in the past.

Tenet provided a slightly different take, suggesting that just because Saddam has such weapons doesn't necessarily mean he'll use them now.

Sen. Carl Levin, D-Mich., chairman of the Senate Armed Services Committee, noted that if the conclusion is that Saddam would be more likely to use weapons of mass destruction if attacked by the United States was "a relevant fact" that Congress should consider as it debates the war resolution.

Levin opposes giving Bush the authority to act against Iraq unilaterally.

Byrd, who has been criticizing the Iraq war resolution daily since the Senate began debate last Thursday, told colleagues at a party luncheon that he planned to make full use of Senate rules to try to derail the legislation, participants said.

Byrd, a former majority leader, is widely regarded for his knowledge and skilled use of Senate rules.

But Daschle suggested the delaying tactics might only be postponing the inevitable -- approval of the measure. Daschle suggested a procedural vote scheduled for Thursday -- essentially to decide whether to stay on the bill or go to something else -- would be a critical vote that will signal the depth of the resolution's overall support.