Japanese politician Ichiro Ozawa, who recently left the ruling Democratic Party of Japan together with dozens of other members of parliament, was expected to announce the launch of a new party on Wednesday, in an attempt to challenge the government.

Ozawa was the main opponent of prime minister Noda’s in the latter’s efforts of promoting a bill that raises the sales tax.

“Ozawa’s departure is a plus for Noda in terms of his policy management because it removes sources of friction and makes it easy to cooperate with main opposition parties,” said Atsuo Ito, an independent political analyst who has worked for both the Democrats and rival Liberal Democratic Party (LDP). “But in terms of numbers, Noda’s government is weakening.”

Ozawa’s new party may play an important role in the political life of Japan, marked by voters’ disappointment at the inability of mainstream parties to solve long-lasting issues such as the stagnant economy, huge public debt and an ageing society.

“If an election is called, it may spur a political realignment. Neither the Democrats nor the main opposition could win a majority. It would be a matter of who is allying with whom,” said a politician close to prime minister Noda.