Prime Minster Shigeru Ishiba doling out ¥100,000 ($670) in gift vouchers to 15 freshman Liberal Democratic Party lawmakers has put him in the political doghouse.

Giving the vouchers, which he said were paid for out of his own pocket, was an ethical problem but not, he added, a legal one. That mattered little to members of his own party, however, who questioned whether Ishiba could lead an already-weak LDP into this summer’s Upper House election, and they wondered whether the opposition parties would pass a no-confidence motion against him that could force him to resign.

But dumping Ishiba before the election, expected at the end of July, carries political risks for politicians on both sides of the aisle.

The LDP and its ruling coalition partner, Komeito, lack a Lower House majority, forcing Ishiba to cooperate with at least one opposition party to pass legislation. Internal LDP rivalries mean there appears to be no clear successor to Ishiba who could quickly unite the party, work well with Komeito and others in the opposition during the remainder of the current session of parliament — scheduled to end in late June — and deal with key allies, such as the United States, from a position of domestic political strength.

For the opposition parties, passing a no-confidence motion would, under Article 69 of the Constitution, either force the prime minister and his Cabinet to resign or result in the dissolution of the Lower House within 10 days, triggering another election just months after the last one in October.

But another Lower House election before the Upper House contest would also force the opposition parties to quickly field candidates. And if the opposition were to lose seats, that could allow the LDP and Komeito to recapture their Lower House majority.

However, if Ishiba was simply replaced by another LDP leader, there is a risk for the opposition that his successor might prove to be more popular with voters than he is when the Upper House poll arrives, making it tougher for opposition candidates to beat LDP candidates.

Constitutional Democratic Party of Japan leader Yoshihiko Noda, whose support would be required for any joint opposition party no-confidence motion, has said it is not an option his party is considering.

“There are calls for submitting a no-confidence motion in the Cabinet or for the Cabinet to step down, but we’re not going to seek one. The LDP may want to replace the top leadership and go into the Upper House election with a fresh image, or dissolve the House of Representatives. But that is not how it will be done,” he told reporters Sunday.

Instead, Noda wants Ishiba to explain himself to the political ethics committees of both houses of parliament — the same committees that heard testimony from LDP members who were caught up in a political slush funds scandal last year.

For all parties, then, deciding what to do about Ishiba's gift voucher controversy in the coming weeks is based on what course of action they see as best benefiting their Upper House election strategies.

Half of the upper chamber’s 248 seats are up for election. Of these, 52 seats are currently held by the LDP and 14 by Komeito, and the two parties need to win at least 50 seats to maintain their majority in the chamber. Failure to do so would would force the LDP and Komeito to scramble to find opposition party votes in both chambers to pass legislation.

Recent public opinion polls on Ishiba and the controversy will play a role in how the prime minister's political supporters and opponents respond. While an Asahi Shimbun poll over the weekend saw his support rate fall to a record-low of 26%, two-thirds of respondents indicated they didn't want him to resign over the problem.

Political commentator Tetsuo Suzuki says what Ishiba does next is likely to impact the polls and whether he escapes the doghouse.

“How will the public perceive the voucher issue, and how will it judge Ishiba’s efforts to explain what happened? The public’s view, as expressed by Cabinet approval ratings, will be a major turning point for the administration,” Suzuki says.