Voting has ended in a key poll for half of the seats in Japan's upper house of parliament.
Final results were expected late at night on Sunday or early on Monday.
With approval ratings well over 60 percent seven months after he took office as prime minister, Shinzo Abe's ruling Liberal Democratic Party is expected to further strengthen its grip on power.
Half of the upper legislative chamber's 242 seats are up for grabs, in what is expected to be the last national election for three years.
Exits polls by Japanese media suggested that the ruling coalition led by Abe had won majority in the upper house.
The Liberal Democratic Party and its junior partner New Komeito claimed at least 71 of the 121 seats available, local broadcaster NHK projected. However, there has not been any official confirmation yet.
"I want to see a stable government. That's the Liberal Democratic Party," said 76-year-old Hiroshi Miyamoto, after casting his ballot for Abe's pro-business, conservative party in the western Tokyo suburb of Hachioji.
Al Jazeera’s Rob McBride, reporting from Tokyo, said: "After today’s vote, Shinzo Abe could end up with kind of majority that he needs to push through his various package of reforms."
"There are a number of different agendas that he has, he has his economic policies that he wants to continue, but also controversially he has his constitutional reforms package that he wants to push though," our correspondent said.
A lot of those going to the polls were voting for Abe’s party because they want to see stability and because they do not see much in terms of alternative to his party in Japanese politics, McBride said.
Control of both chambers will remove political obstacles to Abe's agenda, which includes pushing through reforms to tackle the country's underperforming economy.
They point to the need for reform of the labour market to make it easier for firms to hire and fire workers, participation in a huge free trade pact and a rise in consumption tax, which economists say will help to slow the pace of growth in the already sky-high national debt.
The reforms are the third instalment of an economic policy plan dubbed "Abenomics" that has already seen a slew of government spending and a flood of easy money from the central bank.
Those moves pushed the value of the yen down and sent the stock market soaring, bringing cheer to some sectors of corporate Japan.
However, Abe's detractors say Abenomics is a ruse, part of a tactical power grab that will see the PM return to his conservative social agenda once he has control over both houses of parliament.
They fear this will mean a loosening of Japan's constitutional commitment to pacifism, a boosting of the military and a more strident tone in already-strained relations with China and South Korea, both of which have territorial disputes with Tokyo.
Whatever Abe's intentions, the predicted swing towards his Liberal Democratic Party and their junior coalition allies could give Japan its first long-term prime minister since Junichiro Koizumi, who ruled for the first half of last decade.