The US ambassador to Iraq today urged Iraqi leaders to work harder to achieve key political and security goals.
Zalmay Khalilzad said that successes in Iraq were still possible and could be achieved in "realistic timetable".
Mr Khalilzad was speaking at a news conference with the top US commander in Iraq, General George Casey.
General Casey accused Iran and Syria of providing support to armed groups in Iraq, a move he described as "decidedly unhelpful".
Mr Khalilzad said Iraqi leaders had agreed to a timeline of progress on security and the economy, including changes to the constitution, disbanding militias and a new oil law. He said he believed there would be "significant progress in the coming 12 months".
"They have committed themselves to a timeline for making some of those decisions that I have described," he said. "We will work with them as closely as possible so that they do meet those benchmarks."
October is already the deadliest month this year for US troops in Iraq, with at least 86 killed, boosting domestic pressure on Mr Bush before congressional elections in two weeks.
Opinion polls suggest Mr Bush's Republican party faces severe losses, but he has insisted the United States will not leave Iraq "until we get the job done".
General Casey told the news conference he remained committed to reducing US troop levels as Iraqi forces become more capable, but said: "I can't tell you when that might be."
The US military said last week it was reviewing strategy in Baghdad, where US reinforcements have failed to halt spiralling violence.
US troops today searched part of the Iraqi capital for a missing soldier. Military officials said the soldier, a translator, may have been abducted.
US forces backed by armoured vehicles and helicopters sealed the mixed neighbourhood of Karrada with checkpoints and did door-to-door searches.
The search has revived memories of the kidnapping in June of two US soldiers near Yusufiya, an al-Qaeda stronghold south of Baghdad, in an ambush in which another soldier was killed. Their bodies were later found badly mutilated.
A poll released by CNN yesterday said one in five Americans believed Washington was winning the war in Iraq, a figure halved since December. A similar number believe insurgents are winning, CNN said. Nearly two-thirds oppose the war.