The two top US officials in Iraq have faced criticism from Democrat presidential hopefuls in Congress.
Senators Joe Biden and Barack Obama told military commander David Petraeus and Ambassador Ryan Crocker the troop build-up had failed to achieve peace. ( BBC )
Senator Hillary Clinton said the two men had been dealt a "very hard hand" and said the US government was failing to pursue a coherent strategy.
Gen Petraeus and Mr Crocker were giving testimony on the hearing's second day.
Both repeated their contention that the military "surge" in Iraq was working, and warned against a rapid withdrawal.
White House officials said President Bush would this week announce plans to reduce US troops in Iraq by about 30,000 by next summer - in line with the recommendations of Gen Petraeus and Mr Crocker.
The BBC's Justin Webb, in Washington, says the president's move is an attempt to seize the initiative and to give the impression - whether true or not - that he is driving events.