The Andhra Pradesh Congress president, Mr D. Srinivas, expressed confidence that he would win in the by-election from Nizamabad Urban constituency on Tuesday.
"I am absolutely confident of winning. There is no doubt about it," he told reporters after exercising his franchise at a polling station here.
When asked to comment on reports which claimed that he would become the state's Deputy Chief Minister if he won the bypoll, Mr Srinivas said, "Just forget about all that. This is only an election for a MLA."
On complaints from a group of voters in Nizamabad that their votes were missing, Srinivas said it was a matter to be dealt by the election authorities.
The by-election in Nizamabad was necessitated as the sitting BJP MLA Y. Lakshminarayana quit his post in support of separate Telangana demand.
Mr Srinivas, who had won from Nizamabad several times since 1980, was defeated by Mr Lakshminarayana in the 2009 elections.
The stakes are high for Srinivas this time as he himself claimed several times that he would occupy a "big post" if he wins.
The counting of votes for Nizamabad Urban and 11 other assembly segments in Telangana region will be taken up on July 30.
Meanwhile, about 56 percent polling was reported till 3 pm in the by elections to 12 assembly constituencies in Telangana region of Andhra Pradesh.
Highest polling of 64 per cent per cent was recorded in Huzurabad constituency in Karimnagar district while the lowest polling was recorded at 45 per cent in Nizamabad Urban, State Chief Electoral Officer I V Subba Rao told reporters here
The by-polls have been necessitated as the sitting MLAs had quit their posts in support of separate Telangana demand.