A proposed resolution to withdraw US forces in Iraq by the end of next March failed to get enough votes to move forward in the US senate on Thursday.
Supporters of the bill was unable to get the 60-vote majority needed to overcome procedural hurdles.
They were outnumbered by opposers 48 to 50, according to congressional voting records.
Had the bill passed the senate, the White House is set to immediately veto it.
However, by bringing up the resolution, Democrats once again directly challenged the Bush administration's war power.
Earlier in the day, the House Appropriations Committee endorsed a plan to withdraw all combat troops from Iraq by September 2007.
On a 36-28 vote, it approved a US$124 billion emergency spending bill, which also sets the above deadline for troop withdrawal.
The full House is expected to debate the bill next week.
Both moves are efforts of the Democratic majority in the Congress to limit the Bush administration's war power.
The White House has threatened to veto any bill dictating a troop withdrawal.
(Xinhua News Agency March 16, 2007)
