Japanese Prime Minister Naoto Kan's Democratic Party of Japan (DPJ) and its coalition partner would fail to win the 56 seats, the number needed to control the chamber, in Sunday's upper house election, dpa reported according to news reports.
After polling stations closed at 8 pm (1100 GMT), the Japanese media's exit polls showed the DPJ and its partner the People's New Party would gain fewer than the 56 seats while the main opposition Liberal Democratic Party would gain seats.
Failure to win the majority would make it more difficult for the government to carry out its policy agenda, though the DPJ has a majority in the more powerful lower house.