A quick withdrawal of U.S. forces from Iraq could allow victorious Muslim extremists to fan out into other countries, with some militants going to Afghanistan to fight alongside a resurgent Taliban, Vice President Dick Cheney says.

The vice president, just back from a trip that included unannounced stops in Afghanistan and Pakistan, addressed a conservative conference Thursday night where he sharply criticized efforts by some Democrats to restrict funds for President Bush's troop buildup in Iraq or to place restrictions on their deployment.

While noting that the House already had passed a nonbinding resolution voicing opposition to Bush's Iraq policy, Cheney said that "very soon both houses of Congress will have to vote on a piece of legislation that is binding."

The legislation would, among other things, help pay for the additional 21,500 troops Bush is sending to Iraq.

"I sincerely hope the discussion this time will be about winning in Iraq, not about posturing on Capitol Hill. Anyone can say they support the troops, and we should take them at their word. But the proof will come when it's time to provide the money and the support," Cheney said. "We expect the House and the Senate to meet those needs on time and in full."

The vice president spoke at an annual dinner of the Conservative Political Action Conference. The audience included conservative activists, leaders and policymakers.

Earlier on Thursday, Democratic officials said House Democratic leaders had coalesced around legislation that would require troops to come home from Iraq within six months if that country's leaders fail to meet promises to help reduce violence there.

The plan would retain a Democratic proposal prohibiting the deployment to Iraq of troops with insufficient rest or training or who already have served there for more than a year. Under the plan, such troops could only be sent to Iraq if Bush waives those standards and reports to Congress each time.

The proposal is the latest attempt by Democrats to resolve deep divisions within the party on how far to go to scale back U.S. involvement in Iraq. Rep. James Moran said the latest version has the support of party leadership and said he believes it is final and has the best chance at attracting broad support.

"We're going to report out" a war spending bill "that's responsive to the will of the voters last November and brings our troops home as soon and safely as possible," Moran, D-Va., said in an interview.

During his visit to Pakistan, Cheney expressed concern to President Gen. Pervez Musharraf over Al Qaeda's regrouping inside Pakistan's tribal regions and an expected Taliban spring offensive in neighboring Afghanistan.

"If our coalition withdrew before Iraqis could defend themselves, radical factions would battle for dominance. The violence would likely spread throughout the country and be very difficult to contain. Having tasted victory in Iraq, the (militants) would look for new missions. Many would head for Afghanistan to fight alongside the Taliban," Cheney said.

He said others would head for capitals across the Middle East and work to undermine moderate governments. "Still others would find their targets and victims in other countries on other continents. Such chaos and mounting danger does not have to occur. It is, however, the enemy's objective," Cheney said.

"In these circumstances, it's worth reminding ourselves that, like it or not, the enemy we face in the war on terror has made Iraq the primary front in that war," he added. Then, to laughter and applause, Cheney said, "To use a popular phrase, this is an inconvenient truth."

It was a play on the Academy Award-winning environmental documentary featuring former Vice President Al Gore, "An Inconvenient Truth."

"If you support the war on terror, then it only makes sense to support it where the terrorists are fighting us," Cheney said.