The Democratic Party for the People will seek to implement measures to increase people's take-home pay, its leader Yuichiro Tamaki said in an interview ahead of the Upper House election on July 20.

Tamaki said that the opposition party will aim to win 16 seats in the race for the upper chamber of the Diet, Japan's parliament, as holding a total of 21 seats, including those not to be contested in the upcoming poll, would enable the party to independently submit bills needing budgetary measures.

"We will make it a summer of raising take-home pay," he said, pledging the party's aim of increasing the country's annual gross domestic product to ¥1 quadrillion ($6.95 trillion) in a decade.

Tamaki said that the DPP will work hard to promote investments, to increase education, science and technology budgets to around ¥10 trillion, and to resolve labor supply constraints by raising the minimum taxable income levels. He called the measures "the three arrows of the DPP," in an apparent reference to the "three arrows" of the late former Prime Minister Shinzo Abe's Abenomics economic policy mix.

Tamaki said his party will focus on combating inflation in the Upper House race, arguing that the DPP is the only party seeking to tackle the issue head-on by raising incomes.

He criticized the administration of Prime Minister Shigeru Ishiba, saying that the government has not fulfilled promises of raising the annual taxable income threshold and scrapping a provisional add-on tax rate for gasoline. His party and the ruling Liberal Democratic Party-Komeito coalition agreed last December to aim for raising the minimum annual taxable income level to ¥1.78 million.

Tamaki declined to commit to cooperating with other parties after the Upper House poll.

"Decisions will be based on policy" rather than party, he said.

Regarding cooperation with opposition parties for the July 20 election, Tamaki said, "Basically, we aim to make our party bigger."

At the same time, he noted that the DPP has experience of cooperating with other parties and the Japanese Trade Union Confederation, or Rengo, in certain single-seat constituencies. "I will respect the circumstances and history of each region as much as possible," he said.

Tamaki avoided commenting on whether the DPP will continue policy negotiations with the ruling bloc after the election, saying, "It is unclear whether (the Ishiba administration) will continue."

"We will cooperate where possible in order to achieve our policies, but will not cooperate where we can't," he went on.

Tamaki said his goal of becoming prime minister remains unchanged, while noting that the timing and other related issues depend on the political landscape.

He attributed the DPP's declining support rate in recent media opinion polls to turmoil over the fielding of a candidate under the proportional representation system in the Upper House race. "We will go back to basics and campaign on policies aimed at increasing take-home pay," Tamaki said.