Major opposition parties have decided to support a single candidate in a House of Representatives by-election set to be held in Shizuoka Prefecture on April 26.

The by-election in the prefecture’s No. 4 constituency is now likely to be a de facto one-on-one race between candidates from the ruling and opposition blocs.

At a joint news conference on Tuesday, executives of four major opposition parties — the Constitutional Democratic Party of Japan, the Democratic Party for the People, the Japanese Communist Party and the Social Democratic Party — announced their support for independent rookie Ken Tanaka, 42, in the coming election.

“The political position of the administration of Prime Minister Shinzo Abe will be tested” in the election, said Tetsuro Fukuyama, secretary-general of the CDP, hinting at the opposition camp’s determination to win the poll.

The four parties and Tanaka signed an agreement on 14 policy issues.

Specifically, the agreement set a goal of eliminating use of nuclear power while clarifying opposition to the restart of Chubu Electric Power Co.’s Hamaoka nuclear plant in the prefecture without the consent of locals.

The support across four parties for the unified candidate in the by-election is likely to spur further cooperation between the opposition toward the next Lower House general election.

In the by-election, the ruling Liberal Democratic Party plans to field rookie Yoichi Fukazawa, 43. Its junior coalition partner, Komeito, has endorsed the candidate.

“The election is likely to draw a lot of attention,” said Toshihiro Nikai, secretary-general of the LDP. “We want… a victory no matter what.”

Takashi Tachibana, head of NHK Kara Kokumin o Mamoru To (the Party to Protect the People from NHK) is also considering running in the Shizuoka vote.