Former Environment Minister Goshi Hosono said Friday he will leave the struggling Democratic Party to form a new group, the latest setback for the main opposition party since the abrupt resignation of its leader last week.

"I will leave the party and rise with resolve to set up a new party that can hold power," Hosono, 45, told reporters after informing members of his intraparty group about his departure.

The veteran House of Representatives politician also said he will take the lead in Japan's political realignment and form a new alternative to the ruling Liberal Democratic Party headed by Prime Minister Shinzo Abe.