Japan went to polls Sunday to elect about half of the seats of parliament's Upper House with exit polls suggesting the prime minister's ruling party has kept hold of its comfortable majority.

Sunday's elections are seen as a barometer of public support for the government of Prime Minister Shinzo Abe, which has been in power for six-and-a-half years, with Abe on his way to becoming one of Japan's longest-running leaders.

Although official results are not expected until Monday, exit polling suggests Abe's party and his ally, the Buddhist Komeito, will take around 63 of the 124 Upper House seats up for grabs. Both parties have held more than 60 seats since the last election in 2016, according to figures compiled by Kyodo news.

This would allow the governing coalition to take 130 of the 245 of the seats in the Japanese Senate.

A total of 370 candidates are contesting these elections.

The remaining seats will be voted for in the next election scheduled for 2022 in which three more seats will be added to raise the total number to 248.

Among the issues that the election campaign has focused on are the rise in the Consumption Tax rate planned for October, the reform of the pacifist article of the constitution pushed by Abe to grant more powers to the Self-Defense Forces, and the sustainability of the national pension system.

To promote constitutional reform, which is one of Abe's political priorities, the support of two-thirds of the Upper House is needed, a proportion that is already achieved in the house in its current composition if other parties in favor of the initiative are added.

The Japanese constitution gives more power to the Lower House or the House of Representatives of the parliament (Diet), for which elections are held every four years, and whose decisions prevail over those of the Upper House. EFE-EPA