WASHINGTON —  Sen. John Kerry says President Bush should bring home 20,000 troops from Iraq over the Christmas holidays if the December parliamentary elections there are successful.

Defeated by Bush last year and a potential candidate for the Democratic presidential nomination (search) in 2008, Kerry called for a "reasonable time frame" for pulling back troops rather than a full-scale withdrawal advocated by some Democrats. He said it could be completed in 12 to 15 months.

"It will be hard for this administration, but it is essential to acknowledge that the insurgency will not be defeated unless our troop levels are drawn down ... starting immediately after successful elections in December," Kerry (search), D-Mass., said in a speech Wednesday at Georgetown University (search).

The presence of 159,000 U.S. troops in Iraq is deterring peace efforts, said Kerry, a member of the Senate Foreign Relations Committee.

"To undermine the insurgency, we must instead simultaneously pursue both a political settlement and the withdrawal of American combat forces linked to specific, responsible benchmarks," he said. "At the first benchmark, the completion of December elections, we can start the process of reducing our forces by 20,000 troops over the course of the holidays."

Kerry, who voted to authorize the use of force in Iraq, has been a strong critic of Bush's handling of the war, accusing the president of misleading the public into going to war.

The Republican National Committee (search) argued that Kerry's plan to pull back troops would make American forces remaining in Iraq more vulnerable to insurgent strikes.

"John Kerry is either willing to endanger American forces on the ground or he really believes that ignoring the presence of terrorists is the best policy for the safety of America," said RNC spokeswoman Tracey Schmitt.