After an election that has reduced Japan’s Liberal Democratic party to its weakest parliamentary position in 70 years, Prime Minister Shigeru Ishiba vowed to remain in office to protect the country’s politics from instability. Many suspect, however, that he has guaranteed months of turmoil.

Ishiba’s party, which has governed Japan for all but a few years since 1955, has lost its majority in the lower and upper houses of parliament. Ishiba was in charge in both elections — a snap lower house election called in October and Sunday’s vote for half the upper house seats.

His tenure catches the LDP at a vulnerable moment: its traditional rural support base is ageing and shrinking, and younger Japanese voters have proved more susceptible to online campaigning and social media populism than the party’s grandees anticipated.