Japanese Prime Minister Fumio Kishida on Sunday urged ruling Liberal Democratic Party (LDP) lawmakers to unite as one to win the upcoming House of Councilors election and ensure a stable coalition government.

Kishida, president of the LDP, made the remarks at a party convention, emphasizing the importance of its coalition with its smaller partner Komeito.

He dismissed an emerging view that the relationship between the LDP and Komeito has become awkward over cooperation in the election, which will possibly be held in July.

"Is there any other option than LDP-Komeito that can be entrusted with governing the country when we face history-making challenges? I don't think so," Kishida said at the convention.

"At times, upper house elections have triggered a big political change. Let us unite as one and secure a victory," said Kishida, who was elected LDP president last September.

The House of Councilors election this summer is a key test for Kishida as head of the LDP and also as prime minister, who will be judged by voters on his handling of the COVID-19 pandemic and the economy.

"The stage is set for cooperation in the House of Councilors election. We will look at the situation in each constituency and seek substantive cooperation that will produce results," said Natsuo Yamaguchi, chief of Komeito.