Opposition leader Yukio Edano has said his party is ready to prove it is a viable alternative to Prime Minister Yoshihide Suga's Liberal Democratic Party in this year's general election, despite remaining far behind in public opinion polls.

"We resolve anew to unite and live up to the people's expectations toward the change of power," Edano, leader of the Constitutional Democratic Party of Japan (CDP), said at the party's convention.

Edano criticized Suga's attempts to strike a balance between support for the economy and virus containment as his government continues to struggle to contain the spread of COVID-19 infections.