AIUDF chief Badruddin Ajmal on Thursday filed his nomination papers for the Dhubri Lok Sabha seat, officials said.
Polling for the Dhubri, Kokrajhar, Barpeta and Guwahati Lok Sabha seats will be held in the third phase on April 23.
Leading a procession of his supporters, Ajmal went to the Returning Officer's office and filed his application to contest in the Dhubri seat. In 2014, Ajmal had won from the seat with a margin of 3.63 lakh votes.
Meanwhile, two candidates in the first phase of polling have withdrawn their nomination, leaving 41 aspirants in the fray in Tezpur, Kaliabor, Jorhat, Dibrugarh and Lakhimpur constituencies.
Independent candidates Iqbal Ansari in Tezpur and Purnakanta Deuri in Lakhimpur have withdrawn their papers.
A total of 56 nominations for the second phase of polling in five Lok Sabha seats in Assam were found to be valid after scrutiny on Wednesday.
Karimganj (SC), Silchar, Autonomous District (ST), Mangaldoi and Nawgong will go for polling in the second phase.
The three-phase voting in Assam will take place on April 11, 18 and 23.
For the first phase, the ECI fixed March 28 for last date of withdrawal, while it is March 29 for the second phase.
As per the last summary revision, over 2.17 crore voters, including at least 7.06 lakh first timers, will exercise their franchise in the elections to elect 14 members to the Lok Sabha from Assam.In 2014, the BJP won seven out of 14 Lok Sabha seats in Assam, the Congress and the AIUDF had three MPs each and one member was an Independent.