Presidential candidates -- who lost in Daejeon, South and North Chungcheong provinces -- lost most past elections.
Front-runner Moon Jae-in was leading in the Chungcheong region until May 3, when the ban on the publication of opinion polls was issued.
The voters in the region are traditionally politically centrist, center-right or conservative in general. But they sometimes cast more ballots for liberal candidates, as they did for Kim Dae-jung in 1997 and Roh Moo-hyun in 2002.
It will be interesting to see how the region votes for the three main candidates -- liberal Moon, centrist Ahn Cheol-soo and conservative Hong Joon-pyo -- in the May 9 elections.
The number of voters in the region comes to 4.4 million including the 189,000 in Sejong administrative city.