The BPF has decided not to contest any other Lok Sabha seat and will extend its support to the BJP in all other constituencies in Assam, he added.
Brahma, 68, is the state's social welfare and soil conservation minister, has won the Kokrajhar East (ST) Assembly seat six times in a row since 1991.
She won as an Independent four times and on the BPF's ticket in the 2011 and 2016 polls.
In 2014 Lok Sabha elections, Chandan Brahma of the BPF came third in Kokrajhar, a Scheduled Tribe seat.
Independent Naba Kumar Sarania, a former ULFA militant, recorded a massive victory bagging 6.34 lakh votes compared to 2.79 lakh votes by Independent Urkhao Gwra Brahma, who came second. The BPF candidate got 2.44 lakh votes.
Kokrajhar will go to polls in the third and last phase on April 23.
Several clashes have been witnessed between the Bodo and non-Bodo communities in those districts since 2003 when the BTAD was set up.
According to 2011 census, 30.5 per cent people in BTAD speak Bodo, while Assamese and Bangla are spoken by 26.8 per cent and 23.7 per cent respectively.
Santali, Hindi, Nepali, Kurux, Rabha and other languages constitute the rest.
"We wanted this seat, but it is not possible in the present circumstances. We have some local issues. So, we have left this seat to the BJP," Mohilary said.
He, however, did not elaborate what he meant by "the present circumstances".
Mangaldoi is outside the jurisdiction of the BTAD.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)