The US Senate has voted to demand regular reports from the White House on progress towards a phased pullout of troops from Iraq.
More than 2,000 US troops have been killed in Iraq since 2003
The Republican-controlled body supported the plan in a 79-19 vote.
Senators earlier rejected a Democratic proposal that called on President George W Bush to outline a timetable for the withdrawal.
The move comes after the UK announced it could start pulling its troops out from the beginning of next year.
For months, opinion polls have been suggesting that the American people are losing faith in the ability of the White House to find a way out of Iraq, the BBC's Justin Webb in Washington reports.
Tuesday's bi-partisan vote on the amended proposal suggests that very significant members of the president's own party share that popular concern, our correspondent says.
President Bush has repeatedly pledged to stay the course in Iraq for as long as it takes.
But the concern among many Republicans is that such a stance allows the Iraqi leaders too much leeway in their efforts to bring the country under control, our correspondent says.
Tuesday's proposal also says Iraqis forces should take the lead in providing security for themselves next year to plan for a US pullout.