Washington ? Brushing aside criticism from the White House, Senate Democrats said Friday their next challenge to President Bush’s Iraq war policy would require the gradual withdrawal of U.S. combat troops beginning within 120 days.

The draft legislation also declares the war “requires principally a political solution” rather than a military one.

The provisions are included in a measure that would repeal the authority that lawmakers gave Bush in 2002, months before the invasion of Iraq, and replace it with a far more limited mission.

Democrats have said they are likely to seek a vote on the proposal within two weeks. The odds against it ever becoming law are high, and the White House and Senate Republicans were quick to denounce it.

White House spokesman Tony Fratto said the administration “of course” would oppose an attempt to alter the existing authorization, and he warned that a pullout of U.S. troops could bring chaos to Iraq. “We’re operating under a mandate,” he said.

Senate Republican leader Mitch McConnell of Kentucky dismissed the proposal as an attempt by Democrats to produce “what could best be described as a Goldilocks resolution: one that is hot enough for the radical left wing, but cool enough for party leaders to claim that they are for the troops.”

A spokesman for Senate Majority Leader Harry Reid said the White House is not only confused but also in denial.

“They can spin all they want, but the fact is that President Bush is ignoring a bipartisan majority of Congress, his own military commanders and the American public in escalating the war,” Jim Manley said. “The American people have demanded a change of course in Iraq, and Democrats are committed to holding President Bush accountable.”

As currently drafted, the Democratic legislation says the military “shall commence phased redeployment of U.S. forces from Iraq not later than 120 days” after the bill’s enactment. The goal is to complete the withdrawal by March 31, 2008.

In the interim, the military would be required to transition to a new mission involving “targeted anti-terrorism operations,” as well as providing training and logistical support for the Iraqis and helping them protect their own borders.

The measure also pledges that Congress will “continue to support and protect” the armed forces, renewing a commitment that was included in an earlier nonbinding measure that also criticized Bush’s plans to deploy an additional 21,500 troops.

Republicans blocked action on the measure last week, demanding that Democrats allow a vote on an alternative that would rule out cutting off funds for the troops.