Democratic leaders of the U.S. Congress said on Friday that they would keep pressuring President George W. Bush on a timetable for withdrawing U.S. troops from Iraq.

House Speaker Nancy Pelosi said at a news conference that she would introduce legislation next month to authorize withdrawing American troops from Iraq within 120 days and to complete the withdrawal by April 1, 2008.

The United States would leave some cover forces to fight terrorists and protect U.S. facilities in Iraq, she said.

"But we have the support of the American people, who want this war to come to an end," she said.

Senate Democrats would introduce their own measure in July, Majority Leader Harry Reid said.

But Reid was not sure whether he could get the necessary votes to approve such a bill.

"I don't know if we can or not," he said of clearing the 60-vote hurdle. "We're going to keep pushing, because it's the right thing to do."

At the Pentagon, Defense Secretary Robert Gates said previous legislation that requested progress reports on Iraq in July and September should be followed. "It seems to me that Congress has laid out a sensible timetable and we ought to adhere to it," he said.

The Congress approved a war spending bill in late April which set a timetable to withdraw U.S. troops out of Iraq, but the bill was vetoed by Bush on May 1, the fourth anniversary of his "Mission Accomplished" speech, in which he declared on May 1, 2003,that major combat operations in Iraq had ended.

Currently there are over 150,000 U.S. troops in Iraq, and more than 3,500 American soldiers and tens of thousands of Iraqis have been killed in the country since the war started in March 2003.