Former Democratic Party of Japan leaders Katsuya Okada and Yukio Hatoyama emerged Tuesday as the most likely replacements for President Ichiro Ozawa ahead of the pivotal general election later this year.

Ozawa, who announced his resignation Monday, leaves the biggest opposition party groping for momentum after an unusually timed fundraising scandal left his top aide in jail.

Now the party must scramble to find a candidate strong enough to challenge Prime Minister Taro Aso and the Liberal Democratic Party-New Komeito ruling coalition for power.