The plan would expand the 3,100-strong US contingent of trainers and advisers in Iraq and would mark an adjustment in strategy for President Barack Obama, who is facing mounting criticism for not being tougher in combating Islamic State.
US officials, speaking on condition of anonymity, expressed hope that even a modestly strengthened US presence could help Iraqi forces plan and carry out a counter-attack to retake Anbar's capital Ramadi, which insurgents seized last month.
However, Obama was expected to stick to his stance against sending US troops into combat or even close to the front lines, officials said.
Obama said on Monday the United States did not yet have a complete strategy for training Iraqi security forces to regain land lost to Islamic State fighters, who have seized a third of Iraq over the past year in a campaign marked by mass killings and beheadings.
The fall of Ramadi last month drew harsh US criticism of the weak Iraqi military performance and Washington has begun to speed up supplies of weapons to the government forces and examine ways to improve the training program.
The expected troop announcement was unlikely to silence Obama's critics, who say the modest contingent of US forces is far from enough to turn the tide of battle.
The US deployment would likely entail around 400 trainers, one US official said, adding an announcement was expected on Wednesday. Two other officials also confirmed an expected troop increase of hundreds of troops.
New US training base
US forces have already conducted training at the al-Asad military base in western Anbar but US officials said planning was underway for a new installation near the town of Habbaniya, the site of an Iraqi army base.
A new site would allow US trainers to provide greater support for Sunni tribal fighters, who have yet to receive all of the backing and arms promised by the Shi'ite-led government in Baghdad.
"We are considering a range of options to accelerate the training and equipping of Iraqi security forces in order to support them in taking the fight to ISIL. Those options include sending additional trainers to Iraq," said Alistair Baskey, a spokesman for the White House National Security Council.
General Martin Dempsey, chairman of the Joint Chiefs of Staff, made clear during a visit to Jerusalem that there were no plans to fundamentally alter Obama's military strategy.
Speaking to reporters traveling with him, Dempsey did not say how many extra US troops may be involved in the effort to accelerate the training of Iraqis.
As of last Thursday, 8,920 Iraqi troops had received training at four different sites and another 2,601 were currently in some stage of training, he said.