The Congress is fielding the wife of suspended IPS officer Sanjiv Bhatt against Narendra Modi in the Maninagar constituency in the upcoming Gujarat polls.
Shweta Bhatt is expected to file her nomination papers today, and NDTV reported that she had already started her campaign against Modi.
Speculation that she would run on a Congress ticket had already been high, and it further intensified when she publicly attacked the Chief Minister during a function organised by an NGO in Ahmedabad earlier this month, saying that he made Gujarat "a state of fear".
However, the BJP has pounced on the announcement to allege that this was evidence that the charges leveled against Modi by the IPS official were politically motivated.
Bhatt had earlier accused Modi of meeting with senior state officials, including police officials, during the 2002 communal riots in the state and asked them not to take any action against the rioters.
He had also said that evidence related to the 2002 Gujarat riots has been selectively destroyed and called for an inquiry into the matter.
Bhatt was since charged in a custodial death case that took place in 1990 and another case of abduction, in which he is accused of illegally confining a police official in order to make him give false evidence against the Chief Minister. He was also arrested and subsequently released on bail.
The Gujarat polls will be held in two phases, on 13 and 17 December. The votes will be counted on 20 December.