Polls opened in Japan on Sunday for upper house elections expected to deliver a win for prime minister Shinzo Abe. Half of the 242 seats in the chamber are at stake.
Polls show the Liberal Democratic Party and its allies could secure a majority, meaning the ruling party would control both houses of parliament for the first time in six years.
While not as powerful as the lower house, the upper house is able to block legislation introduced by the government.
The BBC reports no single party currently has a majority, although the Democratic Party of Japan has the highest number of seats. Opposition parties have had enough combined seats to control the upper chamber.
This has resulted in factionalism and multiple changes of prime minister.
"We need political stability to carry out policies," Mr Abe said on Friday. "We will get that political stability by winning the upper house election."
The BBC reports Mr Abe has relatively strong public support for his proposals for economic reform, which seek to revive the economy, stagnant for two decades.