The Democratic Party of Japan suffered a great setback in the Tokyo metropolitan assembly election held on June 23. The party, which won 54 seats in the previous election and became the No. 1 party in the assembly, was reduced to the No. 4 party by garnering only 15 seats. Meanwhile the Japan Communist Party raced to the No. 3 position by getting 17 seats. But the DPJ is still the No. 1 opposition party in the national Diet. With the Upper House election taking place in a matter of weeks, it does not have the luxury of wasting time feeling sorry for itself.

DPJ leader Mr. Banri Kaieda must realize that his party has the mission of rallying middle-of-the-road and liberal forces before the July 21 election. The DPJ must accomplish this urgent task because the right-leaning political forces inclined toward market fundamentalism — as represented by the Liberal Democratic Party, the Japan Restoration Party and Your Party — have already become powerful. If they become lopsidedly strong, voters will be deprived of meaningful political choices. The DPJ must clearly explain to voters the problems that market fundamentalism brings about, namely the expansion of the gap between the rich and the poor, and the shrinking of welfare and other public services provided by the government sector. Such an outcome will only serve to further destabilize Japan’s economy and society.

The DPJ must present policy promises that are distinctly different from the LDP and recapture the minds and votes of the people. In its election manifesto for the Upper House election, the DPJ expressed its opposition to a weakening of the Constitution’s Article 96, as called for by the LDP, the JRP and Your Party. Article 96 is a mechanism to prevent imprudent revisions of the Constitution, including pillars such as the principle of sovereignty resting with people, the no-war principle, the freedom of thought, speech and expression, the freedom of assembly and association. But just expressing opposition to the revision is not enough. The DPJ must fully explain to people how the revision will undermine the basis of constitutional democracy.

In the Tokyo metropolitan assembly election campaign, the LDP hyped Mr. Abe’s economic policy and succeeded in winning the support of voters. Although Mr. Abe’s economic policy has benefited the wealthy and big businesses through higher stock prices and a cheaper yen, it has not resulted in expansion of employment, an increase in wages or a revitalization of local economies.

Simply opposing Mr. Abe’s economic policy will not win the DPJ greater support. It needs to present voters with a clear vision for Japan’s future and convincing measures to achieve it. It also must flesh out measures to promote green energy sources to achieve its promise of ending nuclear power generation in the 2030s.

On the diplomatic front, it will be especially important for the DPJ to consider what steps it should take to settle the sovereignty dispute with China over the Senkaku Islands while containing the rise of aggressive nationalism in Japan.