The big political parties are concerned about voter turnout for Sunday’s Upper House election and its impact on the eventual makeup of the Diet.

Ruling and opposition parties believe interest in the election is weakening, as media reports have suggested the ruling coalition, led by Prime Minister Shinzo Abe’s Liberal Democratic Party, is headed for a comfortable victory.

They predict voter turnout will fall below the 57.9 percent seen in the previous Upper House election in 2010.

“It’s going to be a problem if many of you think there is no need to go to the polls,” LDP Secretary-General Shigeru Ishiba said in a recent campaign speech in Yamagata Prefecture, where the party is projected as being out in front.

The LDP suffered one of the worst losses in the history of domestic politics in the 1998 Upper House election and has had bitter experiences with swing voters.

Another senior LDP official said, “The higher the voter turnout, the better our chances of winning, due to high public support for the party this time.”

For New Komeito, the LDP’s junior coalition partner, which is backed by the major lay Buddhist organization Soka Gakkai, a high voter turnout could be bad news for the party.

“If voter turnout is more than 55 percent, we may lose one seat in the proportional representation segment,” a senior New Komeito official said.

Among opposition parties, the Democratic Party of Japan is expecting an uphill battle in a bid to remain the largest party in the chamber.

A senior DPJ official, who expects voter turnout to be 52 or 53 percent, said, “I’m afraid unaffiliated voters will cast their ballots for Your Party or the LDP.”

The Japanese Communist Party believes high voter turnout will not necessarily work against the party.

“We’ve been able to reach out to those who did not support us in the past,” said a senior JCP official.