TOKYO: Voters went to the polls in central Japan to elect a new governor in a race seen as a key factor influencing when embattled Prime Minister Taro Aso will call a general election.

Four candidates are vying to replace the retiring governor of central Shizuoka prefecture, with results expected later in the day, officials said.

It is one of two elections that will likely influence the decision of Aso, who must call a general election by September. The other is the Tokyo assembly election on July 12.

If Yukiko Sakamoto, a candidate backed by Aso's Liberal Democratic Party (LDP), loses to her main rival Heita Kawakatsu, it would be a setback for Aso, whose poll ratings have plunged below 20 per cent.

Kawakatsu is supported by the main opposition Democratic Party of Japan (DPJ).

The premier, who has been in office less than a year, already faces mounting pressure from within his own party to quit the leadership so a new face can lead it into the general election.

Many pundits agree that the LDP, having lost the upper house in 2007, is likely also to lose its large majority in the powerful lower house to the DPJ.

- AFP/yt