Japan’s Liberal Democratic Party, which has led the country for most of the last seven decades, appeared to be heading toward a major defeat in parliamentary elections on Sunday, as exit polls showed voters shifting to opposition parties that included new right-wing populist groups.
The vote for the less powerful Upper House of the bicameral Diet, as Japan’s Parliament is called, was being closely watched as a referendum on the governing party and its leader, Prime Minister Shigeru Ishiba. Under Mr. Ishiba, the Liberal Democrats have struggled to deal with a variety of issues, including the rising price of rice, a backlash against increased immigration and the threat of tariffs from Washington.
After voting ended, exit polls showed the Liberal Democrats and their coalition partner unlikely to hold on to the 50 seats of their 66 up for re-election that they needed to retain control of the chamber. As many as two-thirds of the 124 seats up for re-election appeared set to go to a host of opposition parties spread across the political spectrum.
Even as ballots were still being counted in dozens of close-fought races, powerful members of the governing party were already calling for Mr. Ishiba to step down to take responsibility for what seemed to be a poor showing. Taro Aso, a former deputy prime minister, said he “couldn’t accept” Mr. Ishiba staying on as prime minister, Japan’s TV Asahi reported.
While Mr. Ishiba said in a television interview on Sunday that his party had not done well, he said he wanted to continue as leader because he still had “important duties to fulfill for the nation.”
But analysts say Mr. Ishiba could struggle to maintain support within his party, which he also led to an election defeat last year that robbed it of a majority in the Lower House. At the time, Mr. Ishiba managed to survive politically by gathering enough votes to form a minority government.
“I don’t see how the L.D.P. stays with someone who has led them to two defeats in both houses,” said Tobias Harris, founder of Japan Foresight, a firm that advises clients on Japanese politics.
If Mr. Ishiba is forced to step down, Mr. Harris and other analysts said, it could create political paralysis at a time when Japan faces tariff negotiations with the Trump administration as well as an increasingly assertive China next door.
The biggest winners in Sunday’s contest were two new nationalist parties, the Democratic Party for the People and Sanseito. Exit polls showed the Democrats poised to more than double their seats to 21, while Sanseito’s presence would grow from one seat before the election to about 12, if results hold.
Both parties have made populist appeals to younger voters, including to cut a national consumption tax that has paid for pensions and other costs to support Japan’s growing population of retirees. During the election, Sanseito promised to help working-age people and put “Japanese First,” an agenda that the party’s leader said was inspired by President Trump’s “America First” movement.
The party won both supporters and critics with its call to stop an influx of immigrants who fill jobs left vacant amid Japan’s declining birthrate, but who Sanseito says threaten social stability.
When asked after exit poll results came in whether he would be willing to join a coalition with the Liberal Democrats, Sanseito’s leader, Sohei Kamiya, said his party would work together only on specific issues.
“We won’t cozy up to them just to get a post” on the cabinet, Mr. Kamiya told supporters.
Voters interviewed at polling stations in Tokyo said that while some of these populist policies were extreme, they wanted to protest the Liberal Democrats, whom they described as out of touch. Most of their anger was directed at the rising price of staples including rice.
“I used to be an L.D.P. voter, but I want change,” said Mika Inoue, a 49-year-old bank employee. “In this election, my focus was on policies that would increase the incomes of the Japanese people. Prices are rising, but incomes are not.”
Hiroshi Sugita, a real estate company owner, said he had switched from supporting the Liberal Democrats to Sanseito.
“The L.D.P..’s policies are so inconsistent, particularly the rice price policy,” Mr. Sugita, 68, said. ”Japan is not growing anymore, the economy is rather in the downward trend and we can’t keep supporting the same party any more.”
