TOKYO — Japanese Prime Minister Fumio Kishida announced Wednesday that he will step down after the ruling Liberal Democratic Party selects a new chief next month, “taking responsibility” for an enduring political funding scandal that has engulfed it for months.

The president of the party serves as prime minister when it holds a parliamentary majority. Speaking at a surprise news conference, Kishida said that he will not seek reelection as party president in a vote scheduled for next month.