The "gross manipulation" had denied a large number of state government employees engaged in poll duty of their constitutional right, BJP spokesman Techi Necha said in a statement.
While pointing out that many employees on election duty could not exercise their franchise due to non-issue of postal ballots, the party sought to know the reason behind such a "major lapse".
It alleged that the election process was "suppressed" by the Congress government in the state with the help of officials who acted as agents of the party.