In the end, Fumio Kishida could not escape the pull of gravity.

Japan’s ruling Liberal Democratic Party will elect its new leader late next month, and in recent weeks, the momentum in Tokyo had been swinging one way: that the unpopular but famously stubborn Kishida would run, and win, as potential successors demurred and bided their time for a better opportunity.

That momentum suddenly ran out Wednesday when, in the midst of the normally lazy bon holiday season, the prime minister announced he wouldn’t seek another term as LDP head, effectively tendering his resignation and throwing the race for Japan’s next leader into chaos.