Key Democratic leaders in the House and Senate have united to call on President Bush to begin pulling U.S. troops out of Iraq by the end of the year, citing an overtaxed military, billions of dollars spent and ongoing sectarian violence.

In a letter to Bush released Monday, the Democrats backed a plan for the "phased redeployment" of troops.

"U.S. forces in Iraq should transition to a more limited mission focused on counterterrorism, training and logistical support of Iraqi security forces and force protection of U.S. personnel," the Democrats wrote.

Bush has consistently said no such pullout will happen until the fledgling Iraqi government can secure its position and Iraq's security forces can defend the country.

Democrats had previously advocated reducing reduce troops levels in Iraq, but were split on the precise approach. During a recent floor debate in the Senate, Democratic Sens. John Kerry of Massachusetts and Russ Feingold of Wisconsin proposed legislation that would require troops to be out of Iraq by July 2007.

Senate Minority Leader Harry Reid, D-Nev., and other Democrats backed a measure that called for a phased redeployment to begin by Dec. 31, but did not set a deadline for all troops to be home.

The recent letter, dated July 30, is significant because — signed by every top Democrat on committees with oversight of military, intelligence and international affairs — it solidifies the Democrats' position and presents a unified front as members head into election season.

The letter also was signed by Reid and Rep. Nancy Pelosi of California, his House counterpart.