The Democratic Party's leadership race, which officially opened Friday for the Sept. 15 vote, should be an occasion for the largest opposition party to publicly demonstrate how it plans to rebuild itself and regain the trust of voters after its failure at the helm of government from 2009 to 2012 and then its poor performance against Prime Minister Shinzo Abe's ruling coalition. The candidates in the race must feel a sense of crisis over the party's current state and show how they plan to turn it around instead of focusing on winning the race on the strength of the party's internal power balance.

The race to succeed outgoing leader Katsuya Okada has emerged as a three-way contest among party deputy leader Renho, former Foreign Minister Seiji Maehara and Yuichiro Tamaki, the party's deputy Diet affairs chief. Renho, the popular Upper House member who is endorsed by many members of the departing party leadership under Okada, announced her candidacy in early August — shortly after Okada said he was not seeking re-election as party head. Maehara, known as one of the party's leading conservative figures, joined the race later on, ending speculation — and reportedly hopes by some lawmakers close to the party leadership — that Renho might become the uncontested choice. Tamaki, with support from many younger-generation DP lawmakers, entered the competition on the very day the campaign kicked off after he managed to secure enough endorsements from his colleagues.

Voting for the new leader will be the party's Diet members, candidates tapped for future Diet elections, local assembly members, rank-and-file members and registered supporters. But the biggest challenge for whoever wins the race will be turning the DP into a party that matters for the broader electorate — instead of just leading a party of dwindling Diet strength and declining voter support. The race should be a process for the party to choose a leader who is up to that task.