Seiji Maehara, president of what was once the biggest opposition Democratic Party, announced Friday he will resign to take responsibility for his "lapse in judgment," which caused disarray among the opposition and helped Prime Minister Shinzo Abe's ruling coalition score a sweeping victory in Sunday's snap election.

"I feel excruciating responsibility for failing to form a united opposition front against the ruling bloc and, as a result, allowing it to maintain a two-thirds super-majority" in the Lower House, a contrite Maehara told a party-wide meeting with rank-and-file members of the DP's Upper House caucus and some independents.

"In the world of politics, results mean everything, but I failed to make the right decision . . . I would therefore like to resign as president," Maehara said, before bowing deeply.