BBC: Japanese Prime Minister Shinzo Abe's ruling coalition is on course for a resounding victory in Sunday's general election, according to exit polls.
One poll put Mr Abe's Liberal Democratic Party-led (LDP) coalition at 311 seats, allowing it to retain its two-thirds "super majority".
Other polls showed the coalition slightly below the two-thirds mark.
The majority is vital to Mr Abe's ambition to revise Japan's post-war, pacifist constitution.
Article 9 of the constitution, enacted by the country's American occupiers in 1947, calls for the complete renunciation of war.
Japan has worked around the rule by stating that its army exists for the purposes of defence, but Mr Abe has long made it clear that he wishes to revise it.
A win in the election raises Mr Abe's chances of securing a third three-year-term as leader of the LDP when the party votes next September.
That would give him the opportunity to become Japan's longest serving prime minister, having been elected in 2012.
Japan went to the polls on Sunday as Typhoon Lan lashed parts of the country. Mr Abe called the election early amid rebounding approval ratings and disarray among the opposition.
Speaking to the BBC, one observer described voting for Mr Abe's Liberal Democratic Party as TINA, or "there is no alternative".
What impact, if any, the typhoon had on turnout remains to be seen. The category four storm brought strong winds and heavy rain to the south of the country, causing flights to be cancelled and rail services to be disrupted.
It is expected to blow into the Tokyo area early on Monday, the Japan Meteorological Agency said.
Mr Abe announced the election on 25 September, saying he needed a fresh mandate in order to deal with the "national crises" facing Japan.
The crises include North Korea, which has threatened to "sink" Japan into the sea. Pyongyang has also fired two missiles over Hokkaido, an island to the north.