Prime Minister Shigeru Ishiba of Japan said on Sunday that he planned to resign, plunging the country into deep political uncertainty in a turbulent time.

Japan is grappling with rising right-wing populism at home and heightened unpredictability from its key ally, the United States. Mr. Ishiba, who was elected to lead the governing Liberal Democratic Party just last September, is choosing to step down to prevent a split within the party, he said in a news conference in Tokyo. New york Times reported.

Several prominent members of the Liberal Democrats have called for a vote to be held on Monday on whether to hold an extraordinary leadership election, nearly two months after suffering a huge setback in parliamentary elections in which new right-wing populist groups gained support. The blow left the Liberal Democrats, who have led Japan for all but five of the last 70 years, a minority party in both chambers of the Diet, the country’s Parliament.

Throughout his tenure, Mr. Ishiba has struggled to win voter support amid persistent inflation, which has remained above 2 percent for the past three years. His government has also been damaged by an ongoing shortage of rice, Japan’s staple grain, that many believe has been caused by longstanding government policies that curb production.

The July election results exposed a deepening generational fissure altering the nation’s politics. While traditional liberal opposition parties campaigned on platforms of tax cuts for households, the biggest gains were made not by them but by a new group of parties that drew younger voters with stridently nationalist messages.

Mr. Ishiba’s government has also had to manage increasingly tense relations with the United States since President Trump’s re-election. Japan and the United States took months to negotiate a trade deal that left Japanese exports with a 15 percent across-the-board tariff. Even after the agreement was reached, central details remain unresolved, including a Japanese pledge to invest $550 billion in the U.S. economy.

Until recently, Mr. Ishiba appeared determined to remain in office despite consistently low approval ratings. Following the party’s losses in the July upper house elections, he had rejected calls from fellow Liberal Democrats to resign.

Speaking on Sunday, Mr. Ishiba said that he had ultimately decided that he should take responsibility for the past year’s election results.