The Democratic Party for the People may cooperate on policies with the ruling coalition led by Prime Minister Shigeru Ishiba but will not join the framework outright, its chief said Tuesday after the opposition party surged in influence after the weekend's general election.

Japan faces political uncertainty as the Liberal Democratic Party and its junior partner Komeito, which lost their majority in the powerful House of Representatives, must seek support from opposition parties and independents to pass bills and run a stable government.

"We will do our utmost to realize our policies. We are not entering the coalition," DPP leader Yuichiro Tamaki told a press conference.

Tamaki said DPP officials at different levels have been in contact with their counterparts in the LDP and other opposition parties over whether and how to cooperate.

He sounded positive about holding talks with Ishiba and Yoshihiko Noda, who heads the main opposition Constitutional Democratic Party of Japan, saying he will not refuse to do so if requested.

The DPP quadrupled its seats from seven to 28 in Sunday's election, which saw the ruling bloc secure 215, short of the majority line of 233. The CDPJ won 148 seats.

In a Kyodo News survey conducted after the election, 53 percent of respondents said they do not want the LDP-Komeito government to remain after their election defeat, against 38.4 percent of those in favor.

Ishiba, who heads the LDP, has dismissed the idea of expanding the ruling coalition now but said he was open to working with opposition parties on a policy-by-policy basis.

"If the ruling bloc sticks to the same ideas and playbook on decision-making, it will be difficult to maintain the government because they don't have a majority. We want them to listen humbly to the voices of the people," Tamaki said.

Still, the DPP will not be unnecessarily confrontational, Tamaki said, adding, "If the opposition tries to block everything, we can't keep the country going."

The ruling coalition lost majority control of the 465-member lower house for the first time in 15 years.

Both the LDP and the CDPJ are expected to accelerate efforts to secure support for their own leaders to become the next prime minister in the days ahead.

Tamaki said his fellow DPP lawmakers would vote for him, when parliament selects the next Japanese prime minister during a special session next month.

If no one receives majority support in the lower house, now a possibility after the election, the vote to choose the next prime minister will go to a runoff between the top two contenders, likely Ishiba and Noda.

Tamaki's stance can be taken as de-facto approval for Ishiba because voting for candidates other than the top two would be invalid in the runoff.

"Even if we vote for Mr. Noda, we cannot compete with the LDP-Komeito coalition" in terms of votes, Tamaki said.

Tamaki's party prioritizes boosting people's incomes. It stresses the need for fiscal spending and easy monetary policy to achieve wage growth above the rate of inflation.

One of its top priorities is to raise the income threshold for people to start paying tax on their earnings to 1.78 million yen ($11,600) from the current 1.03 million yen.