Katsuya Okada, deputy leader of the Democratic Party of Japan, announced Thursday he will seek election to the top post and pledged to rebuild the party after it lost the public’s trust during its three-year debut in power through 2012.

“I want to drastically rebuild the party and to transform it into the one that can face the Liberal Democratic Party, and take a firm grip on Japanese politics,” Okada said during a news conference in Tokyo. “This could be the last chance for the DPJ to regain power.”

The largest opposition force will hold its presidential election on Jan. 18.

Okada stressed the need for the party to become more united and promised to use a firm hand. He said discussion is important, but once a policy decision is made, all members should stick to it. Otherwise, he said, the DPJ can not regain the public’s trust.

The race to replace outgoing President Banri Kaieda will likely be a battle between veteran Okada, 61, and former DPJ Secretary-General Goshi Hosono, 43, who threw his hat into the ring earlier. Kaieda resigned after losing his seat in the Dec. 14 Lower House election.

Okada, considered a policy expert, is no newcomer to DPJ leadership elections. He has run for president several times since 2002, when he lost to Naoto Kan, who later went on to become prime minister. Okada headed the party from 2004 to 2005 but resigned after the DPJ’s devastating defeat to the Junichiro Koizumi-led Liberal Democratic Party in the snap Lower House election of September 2005.

When the DPJ was in power between September 2009 and December 2012, Okada served as foreign minister and deputy prime minister.

The next leader will face the difficult task of rebuilding the party after its dismal performance in the Dec. 14 election, which saw the LDP-Komeito coalition retain its two-thirds supermajority for the second consecutive time.

Asked about possible realignment with Ishin no To (Japan Innovation Party), the second-largest opposition force, Okada said such a move would be hard unless they can resolve significant policy differences.

But he said he believes the DPJ should continue to seek cooperation from other parties in the Diet and in elections.

Hosono, meanwhile, is believed to be willing to start merger talks.

Former administrative reform minister Renho, 47, has also said she wants to enter the race, sending out a tweet Tuesday saying: “I will challenge the presidential election. The hurdle is high. But I want to face it.”

But there is some doubt whether she can gain the 20 recommendations from party members needed to join the campaign.

Another rumored candidate, Seiji Maehara, 52, a former head of the party, has decided not to run.