The by-election was necessitated by death, in April, of Kerala Congress-Mani founder K.M. Mani, who represented the constituency since 1967.
With five legislators, Kerala Congress-Mani is the third-biggest constituent of the UDF.
Addressing media soon after his candidature was announced, Pulikunnel, a close aide for Mani for nearly a quarter of a century and overseeing his election campaign, said he is overwhelmed by the decision.
"There are issues still to be sorted out with (faction leader) P.J. Joseph and in Pala, it is the iconic K.M. Mani and his memories that are going to keep the election campaign going forward. If Joseph continue to be adamant, I will not bow before anyone to get the party's symbol (two leaves), because the symbol here in this constituency is 'Mani'," he said.
After Mani's death, the party split into two factions one led by his son and Rajya Sabha member Jose K. Mani and the other by Joseph.
Joseph, all along, was against fielding Jose K. Mani's wife Nisha Jose Mani and this led to a war of words between the rival factions, causing tension to the Congress leadership.
Reacting to the development, Joseph said he has always stood by the decision of the UDF and here too, he will stand by its decision.
However, in a dig, he said: "Did you not hear what the candidate (Pulikunnel) said when he was asked about the symbol... so if he does not want (it), then does anything more need to be said?"
But senior Congress leaders like Oommen Chandy and Ramesh Chennithala, along with Indian Union Muslim League leader P.K. Kunhalikutty, are confident that they will be able to swing around Joseph.
"All knows there are issues in the Kerala Congress-Mani and we are confident that whatever difference of opinion persists, things will be ironed out soon," said UDF Chairman and Leader of Opposition Chennithala.
Meanwhile, NCP leader and film producer Mani C. Kappen, 63, contesting for the fourth consecutive time, has already hit the campaign trail and the BJP-led NDA's candidate will be announced on Monday.
( With inputs from IANS )