The Prime Minister's appearance had originally been put off until after polling day to avoid it becoming a key election issue.
But opposition parties, led by Nick Clegg, the Liberal Democrat leader, have forced both Mr Brown and Sir John Chilcot, the chairman of the inquiry to think again. An announcement is expected this morning.
Mr Clegg gave Mr Brown a torrid time at Prime Minister's Questions last week over his absence from the inquiry despite most of the other key government figures in the Iraq invasion giving evidence including Alastair Campbell, Geoff Hoon and Jack Straw.
Tony Blair will appear in front of Sir John's inquiry team in a week's time.
Mr Campbell, who was Mr Blair's main spokesman and strategy adviser in 2003, told Sir John's committee that Mr Brown was a member of the inner circle that made the key decisions in the period leading up to the invasion.
Mr Clegg said that voters needed to be able to judge how Mr Brown was involved in the decision-making in the run up to the invasion in 2003. He taunted Mr Brown by asking what he had to hide.
In this week's evidence Mr Hoon, the former defence secretary, said that Mr Brown, the then Chancellor, had not made funds available for important equipment including helicopters.
Mr Brown has publicly insisted he has "nothing to hide" and has told Sir John he was willing to appear "at any time" the inquiry should wish.
This week Mr Brown wrote to Sir John to say that he would be prepared to give evidence before the election. It is likely to happen next month.
The Prime Minister will hope that the public will not have their memories reawakened and that the division that Iraq caused in Labour ranks and among its supporters will not hit his election hopes.
