TOKYO — Shigeru Ishiba likes the nitty gritty of policy, cigarettes and making models, but his dream job as Japanese prime minister could go up in smoke today.

Opinion polls suggest that Ishiba’s coalition could lose its majority in upper house elections today, a result that might push him to resign.

The Liberal Democratic Party (LDP) has governed Japan almost continuously since 1955, but whether anyone wants to replace Ishiba is another matter.

“I wonder who else wants the job,” Masahisa Endo, politics professor at Waseda University

Ishiba, 68, a self-confessed defence “geek”, is the son of a regional governor and is from Japan’s small Christian minority.

He won the party leadership in September, on his fifth try, to become the LDP’s 10th separate prime minister since 2000, all of them men.

Ishiba pledged to “create a new Japan” and revitalise depressed rural regions, and to address the “quiet emergency” of Japan’s shrinking population.

He immediately called lower house elections for October but that backfired spectactularly, with the LDP suffering its worst result in 15 years.

That robbed the LDP and its coalition party Komeito of their majority, forcing them to bargain with opposition parties to pass legislation.

Ishiba’s policies on bringing down inflation and spurring growth have “flip-flopped” as a result, said Stefan Angrick at Moody’s Analytics.

“Ishiba’s government has boxed itself in, promising only some belated and half-hearted financial support that will do little to improve the demand outlook,” Angrick said.

The government’s popularity ratings have plummeted, with voters angry about price rises, especially for rice that is twice as expensive as a year ago.