Japan's two major opposition parties merged Thursday and elected a new leader as they try to strengthen their standing ahead of a possible snap national election.
The ruling Liberal Democratic Party will pick a successor to outgoing Prime Minister Shinzo Abe next week, and several top political figures have suggested the next leader may call a quick election.
The opposition parties and several independent lawmakers formally cemented an alliance in response, becoming the Constitutional Democratic Party of Japan, and elected vocal Abe critic Yukio Edano as their new leader.
"Now our true battle begins," Edano said after his election.
"If they (the LDP) avoid full policy debates and dissolve the parliament for their own selfish reasons, let us take on the fight and serve as the alternative choice for voters," he said.
The new bloc commands 149 seats in the national Diet, compared with the dominant LDP's 394 lawmakers.
The LDP votes Monday on their new leader, who is certain to win a parliamentary vote two days later and become the country's next prime minister.
Abe advisor and chief cabinet secretary Yoshihide Suga is widely expected to win the ballot.
He has been circumspect on the possibility of a snap election, to which the LDP's coalition partner is reportedly opposed.
But Defence Minister Taro Kono told an international online event Wednesday that he expected a vote next month.
Despite the new grouping, Japan's opposition is still viewed as fractious and weak.
And public sentiment towards the opposition remains coloured by the experience of the now-defunct Democratic Party of Japan, which held power from 2009-2012.
Endless infighting within the party -- including during the 2011 tsunami disaster and the Fukushima nuclear meltdown -- aggravated policy missteps and flip-flops that saw them voted out.
The LDP, which has governed Japan for all but a handful of years since it was formed in 1955, returned to power in 2012 with Abe at the helm.