He handed over his resignation letter to Chief Minister N Rangasamy just as the latter was about to leave the Assembly during lunch hour.
Later, he submitted his resgination letter in the office of the Speaker as he was not present there, official sources said.
Nehru told reporters that he had waited until yesterday for an announcement by the Chief Minister of the candidate for the biennial poll.
Nehru said that the ruling All India NR Congress legislators have been approaching him seeking clarification as to who would be fielded for the poll.
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"I have not been able to give any firm reply to them as nothing is known, despite I being a whip, as to who has been finalised for being the AINRC nominee for the poll," he said.
He charged that there has been an 'inordinate delay' in the announcement of the candidate by Rangasamy with only two days left for the filing of nominations.
The election was necessitated as the term of office of the sitting member, P Kannan (Congress), ends on October 6.