Japanese media said it was a record-low result in the key local election for the Liberal Democratic Party (LDP), which has led the country almost continuously since 1955.
Public support for Ishiba, who took office in October, has been at rock-bottom for months, partly because of high inflation, with rice prices doubling over the past year.
The LDP took 21 Tokyo assembly seats in Sunday’s vote, including three won by candidates previously affiliated with the party but not officially endorsed following a political funding scandal.
This breaks the party’s previous record low of 23 seats from 2017, according to the Asahi Shimbun and other local media.
Tomin First no Kai, founded by Tokyo governor Yuriko Koike, increased its seats in the 127-member assembly to 31, becoming the largest party.
“This was a very tough election,” Shinji Inoue, head of the LDP’s Tokyo chapter, said Sunday as exit polls showed a decline in the party’s seats.
The funding scandal “may have affected” the result, while policies to address inflation “didn’t reach voters’ ears very well” with opposition parties also pledging to tackle the issue, Inoue said.
Within weeks Ishiba will face elections for parliament’s upper house, with reports saying the national ballot could be held on July 20.
Voters angry with rising prices and political scandals deprived the 68-year-old’s ruling coalition of a majority in the powerful lower house in October, its worst general election result in 15 years.
Polls this month showed a slight uptick in support, however, thanks in part to policies to tackle high rice prices.
Not including volatile fresh food, goods and energy in Japan were 3.7 percent higher in May than a year earlier.
To help households combat the cost of living, Ishiba has pledged cash handouts of 20,000 yen (US$139) for every citizen ahead of the upper house election.
The opposition Democratic Party For the People (DPP) won seats for the first time in the Tokyo assembly vote, securing nine.
The DPP’s campaign pledge for the July election includes sales tax cuts to boost household incomes.
Sunday’s voter turnout rate was 47.6 percent, compared to the 42.4 percent four years ago, according to local media.
A record 295 candidates ran – the highest since 1997, including 99 women candidates, also a record high.
The number of women assembly members rose to 45 from 41. (AFP)
