Senior officials in the White House have said that the State Department is going to remove the Iranian dissident organisation, Mujahadin-e-Khalq (MeK) from the US list of terrorist organisations.
The officials said the decision would be announced formally next week.
The group has renounced violence, while still calling for regime change, and is thought to have provided the US with intelligence on Iran's nuclear programme.
US Iranians spent millions of dollars to enlist a wide range of US politicians to support the deproscription of the organisation, but only three years ago the US arrested several pro-MeK activists for raising funds for a banned terrorist organisation.
Now members of congress 'openly praise' the organisation.