The US military commander in Iraq is set to announce that the US will withdraw 4,000 of its soldiers from the country by the end of October.
General Ray Odierno is due to tell the House of Representatives Armed Services Committee on Wednesday that the US is speeding up its military withdrawal to complete it by September 2010.
In an advance copy of his address, Odierno said: "We have approximately 124,000 troops and 11 Combat Teams operating in Iraq today. By the end of October, I believe we will be down to 120,000 troops.
"As we go forward, we will thin out lines across Iraq in order to reduce the risk and sustain stability through a deliberate transition of responsibilities to the Iraqi security
Odierno told the New York Times newspaper separately that if the elections in January went smoothly, the US could speed up the troops withdrawal.
"If we get through successful elections, and you seat the government peacefully, that provides another level of stability. That will help to reduce tensions," he said in an interview published on Wednesday.
The Odierno document said the number of US contractors in Iraq has dropped from 149,000 in January to just over 115,000, saving over $441m. Nearly 100 US bases have been closed.
Other quotes from his speech said that Iraq security is improving, but there are still some sources of potential conflict.
"Al-Qaeda in Iraq, Sunni extremist groups, and Shia militant groups continue to pose threats to stability as they seek to exploit political fissures, destabilise the government and undermine the progress made to date," he is expected to say.
The US administration earlier said that after the end of the US combat mission on August 31 next year, a force of 30,000 to 50,000 troops will remain.
These soldiers will train and equip Iraqi forces and protect provincial reconstruction teams, international projects and diplomatic staff.
Violence has fallen sharply in Iraq since the 2003 US-led invasion. Still, roadside bombs, shootings and suicide attacks remain common.
The northern city of Mosul is ranked as one of the most dangerous city in the country.
Overall, attacks in the city from June through August last year compared to the same period this year shows a drop of 44 per cent, but residents still live under a constant threat of violence.
Al Jazeera's Omar Al Saleh, reporting from Mosul, said: "This city has witnessed several military operations in the past trying to calm it down.
"But it is still gripped by bombings and assassinations nearly on a daily basis. People here say it’s all because of politics and that they have really had enough."