TOKYO—Japanese Prime Minister Sanae Takaichi was on track to lead her party to a thumping victory in parliamentary elections, handing her a powerful mandate to deepen ties with the U.S. and rev up Japan’s economy.
The performance is a vindication for the 64-year-old conservative, who called the risky snap vote during a snowy Japanese winter only three months after taking office.
Her gamble was that her straight-talking appeal to voters would cement her grip on power amid challenges including sluggish economic growth and worsening relations with Beijing.
Takaichi’s Liberal Democratic Party and its coalition partner, the Japan Innovation Party, were on course to win around 300 seats in the 465-seat lower house in Japan’s parliament, according to projections by public broadcaster NHK, a substantial majority and a big increase on the combined 230 they held before the vote.
The LDP alone was projected to win a majority of seats, according to NHK, a turnaround in the party’s fortunes after more than a decade of coalitions.
“We stand at a crossroads that will profoundly transform our nation,” Takaichi said Saturday in a message on social media, urging supporters to turn out and vote.
The victory reflects Takaichi’s personal popularity. Voters were enthused by what they saw as her decisiveness and frank style of communication, as well as her optimism and outsider status as a woman in a male-dominated political world. Many braved heavy snowfalls in parts of the country, which had been feared a deterrent to voters.
“I like how Ms. Takaichi is proactive, acts quickly, and sticks to her words,” said Naoya Nakanishi, who was voting Sunday as snow fell near the Tokyo Dome baseball stadium. “She promptly addresses issues directly affecting people’s lives,” he said.
Takaichi also benefited from a poor showing by the newly formed Centrist Reform Alliance, which united two opposition groups to challenge the LDP but failed to ignite voter enthusiasm.
Takaichi is a pro-U.S. leader who has pledged to ramp up defense spending and wants to bolster Japanese industry to make Japan the U.S.’s indispensable partner in Asia.
While other traditional U.S. allies have struggled to respond to President Trump’s enthusiasm for tariffs and disruptive foreign policy, Japan under Takaichi is doubling down on the U.S. alliance, a reflection of Tokyo’s pragmatism and a recognition that loosening ties is unthinkable when confronted with an increasingly assertive China.
“Japan has no option but a close relationship with the U.S. for its security,” said Gerald Curtis, an expert on Japanese politics at Columbia University.
Takaichi and Trump struck up a rapport when the U.S. president visited Tokyo in October, together hailing a new golden age of U.S.-Japan relations. He endorsed her leadership ahead of the election in a message on his Truth Social network, describing her as “strong, powerful and wise.”
She is due to travel to Washington for a summit with Trump next month, where among other things she will be seeking reassurance that the U.S. remains committed to regional security in Asia. The U.S. has around 60,000 military personnel stationed in Japan.
Her trip precedes a planned summit between Trump and Chinese leader Xi Jinping in Beijing in April. Trump’s dealmaking instincts have stoked anxiety in some quarters in Asia that he might be tempted to cede U.S. influence in the region to Xi in exchange for a bumper deal on trade, though U.S. officials say such concerns are unfounded.
The strength of Takaichi’s performance suggests voters approve of her handling of China, which has heaped pressure on Japan over remarks she made about Taiwan.
Takaichi said in November that Japan could be dragged into any military conflict over the self-ruled island democracy, which Beijing views as a Chinese territory to be seized by force if necessary. Beijing reacted angrily, saying Taiwan is a purely domestic affair. Reprisals have included squeezing Japanese companies’ access to critical minerals and magnets that are essential to manufacturing. But Takaichi has declined to retract her remarks, saying she was only stating longstanding, if largely unspoken, Japanese policy.
On the domestic front, Takaichi’s main challenge will be to soothe concerns in jittery financial markets that her plans for more borrowing and spending won’t stoke inflation, while also addressing voter dissatisfaction over stagnant living standards.
Write to Jason Douglas at jason.douglas@wsj.com and Junko Fukutome at junko.fukutome@wsj.com