Reddy, who is TDP's candidate from Puttaparthi assembly constituency, had visited a burial ground here to pay tributes to his late wife, where he collapsed on Wednesday.
The TDP leader's kin and followers immediately took him to a nearby hospital. His condition is said to be stable and is under observation.
Further details are awaited.
Elections to the 175-member Andhra Pradesh Assembly are scheduled to be held on April 11 simultaneously with the Lok Sabha polls. The counting of votes will take place on May 23.
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