M. Continuo
Japan PM party takes big election hit - exit polls
The Democratic Party of Japan (DPJ) and its tiny partner, the People's New Party, were set to lose their combined majority in the upper house, the polls showed.
The Democrats were expected to win just 47 seats, far short of Kan's goal of winning all 54 seats that the party had up for grabs, leaving him vulnerable to a challenge from inside his own party.
The Democrats, who have relied on the People's New Party to control the upper house, will almost certainly stay in power by virtue of their majority in parliament's lower house.
But they will need to seek new partners to control the upper chamber, complicating policymaking as Japan struggles to engineer growth and rein in public debt nearly twice the size of GDP.
The Democrats swept to power last year promising to cut waste and focus spending on consumers to boost growth. Public backing nosedived due to indecisive leadership and while government ratings rose when Kan took over last month, they slipped after he floated a rise in the 5 percent sales tax to help rein in debt.
(Reporting by Linda Sieg and Yoko Nishikawa; Editing by John Chalmers and Rodney Joyce)