Yuichiro Tamaki, who was reinstated as leader of the opposition Democratic Party for the People on Tuesday, hit the ground running on his first day back, saying his party will aim to nearly double its Upper House seats in this summer’s election.

With his return after a three-month suspension from party posts due to an extramarital affair, the DPP hopes to move beyond unsuccessful talks with the ruling Liberal Democratic Party-Komeito coalition, and focus on the Upper House election, in which the DPP aims to increase its seat count from 12 to 21.

Tamaki’s reinstatement comes after senior DPP leaders failed last week to convince the coalition to raise the tax-free income threshold from ¥1.03 million ($6,900) annually to ¥1.78 million. The LDP and Komeito agreed to raise the threshold to only ¥1.6 million.

“We weren’t strong enough (in our negotiations), and feel a sense of shame,” Tamaki said at a news conference Tuesday, though he praised senior party leaders who negotiated with the ruling coalition during his suspension.

With Tamaki — the face of the party — back in the driver’s seat, the DPP will now focus on shoring up voter support for this summer’s Upper House election over the remainder of the current session of parliament, which is expected to end in late June.

“The significance of having 21 Upper House seats is that we would then have the right to submit bills by ourselves,” Tamaki said.

That, however, could be a tall order, he admitted.

“As five of DPP Upper House members are not standing for election this time, we have to win 16 seats total (to reach 21) — a very high target that would give us the right to submit bills requiring a budget,” he said.

The DPP pulled off a surprise in last October’s Lower House election, quadrupling its seats from seven to 28.

The LDP and Komeito lost their majority and were reduced to a minority government that is forced to seek the support of at least one opposition party in order to secure the votes needed for passing the budget and other legislation.

The DPP, which drew a lot of support from younger voters due to its pledge to raise the income tax threshold, initially appeared as the coalition's likeliest target for collaboration.

But Tamaki’s reprimand created a leadership vacuum within the DPP, which was unable to get its way with the LDP and Komeito. Instead, the ruling coalition struck a deal with Nippon Ishin no Kai on its signature policy of free high school education in exchange for supporting the budget for the fiscal year 2025 starting April.

Despite the DPP's opposition, the budget cleared the Lower House on Tuesday on the votes of the LDP, Komeito and Nippon Ishin, and it will now head to the Upper House.

Tamaki has left the door open for cooperation with other major opposition parties during the ongoing parliamentary session on another policy dear to his party — lowering gasoline prices by abolishing a provisional tax from April.

Nippon Ishin has indicated that it would be extremely difficult to get support for the DPP proposal from local governments.

But Tamaki is holding out hope that Nippon Ishin would back the DPP on the issue.

Staff Writer Himari Semans contributed to this report.