Thousands voted here in a by-election in the Radhakrishnan Nagar assembly constituency where Tamil Nadu Chief Minister J. Jayalalithaa is pitted against a CPI candidate.

Election officials said an estimated 35.5 percent of the some 250,000 electorate had voted across the 230 polling centres by midday. At 10 a.m., the polling percentage was 13 percent.

AIADMK general secretary Jayalalithaa is seeking re-election to the assembly.

While there are 28 candidates in the fray, only the Communist Party of India’s C. Mahendran is viewed as a serious opponent against Jayalalithaa, who is widely expected to win.

There are 26 other independents and candidates from small parties including social activist K.R. Ramaswamy, popularly known as “Traffic Ramaswamy”.

Ramaswamy on Saturday accused AIADMK cadres of blocking his car and entering into an argument with him. He vowed to lodge a police complaint.

The polling will close at 5 p.m. The votes will be counted on June 30.

Schools and colleges in the constituency were closed.

Opposition parties like the DMK, the PMK, the DMDK, the Congress, the BJP and the MDMK have stayed away from the contest.

However, the two Left parties – CPI and CPI-M – have fielded Mahendran as their joint candidate.

The Election Commission has introduced a E-Netra system (Election Novel Electronic Tracking and Rapid Action System) in the constituency to observe the model code of conduct, monitor the expenditure by candidates, and redress complaints through a single window.

For the first time in India, the poll panel has introduced Electors Assistance System (EASY). Under this, voters in Radhakrishnan Nagar can get all election details. This facility is available through email, SMS and E-Netra MobileApp.

The Radhakrishnan Nagar constituency fell vacant after AIADMK member P. Vetrival resigned to facilitate Jayalalithaa’s re-election to the assembly.

Jayalalithaa, elected from Srirangam in 2011, lost that seat and the chief minister’s post after a trial court in Bengaluru convicted her in the disproportionate assets case.

The Karnataka High Court upheld her appeal and acquitted her of all charges. Jayalalithaa was again sworn in as chief minister, but she has to get elected to the assembly within six months.

The Karnataka government has gone on appeal against the high court order in the Supreme Court.