Voters in Taiwan shocked their government Saturday with a clear message that’s sure to resonate from Washington to Beijing — not to mention Moscow and Brussels. The message, after Taiwan government candidates suffered heavy losses in local elections: We’re not interested in confrontation with China.

The message was powerful enough to bring about the resignation of Taiwan’s president, Tsai Ing-wen, as leader of her ruling party and elevate the influence of the Kuomintang, the Nationalist Party that held power in China before the victory of Mao Zedong’s Red Army in 1949.

Ms. Tsai remains president of “the Republic of China,” Taiwan’s formal name, but stepped down from leadership of her Democratic Progressive party after its candidates lost key races, including that of mayor of Taipei, the capital. The upset in a number of elections portends the revival of the Kuomintang.

The Kuomintang, known as the “Nationalist” party, held sway over Taiwan for about half a century after the KMT leader, Chiang Kai-shek, led his forces from the mainland before their defeat. The winner as mayor of Taipei in the latest vote is Chiang’s great-grandson, Chiang Wan-an.

“I will let the world see Taipei’s greatness,” he exulted after his victory.

In one of history’s great ironies, the KMT, a conservative grouping with strong trade ties with Communist China, has come in recent years to oppose the anti-Beijing policies of President Tsai. Her policy has seemed to harden after President Xi Jinping ordered military exercises around Taiwan after Speaker Pelosi visited the island in August.

Chiang Kai-shek insisted that Taiwan remain “the Republic of China” and vowed eventually to return to the mainland, whose communist regime Mao named the “People’s Republic of China.” Over the years, though, the outlook of old-time business interests within the KMT has shifted dramatically.

Now, with flights daily between mainland and Taiwan cities, they would prefer to tamp down the confrontation and focus on trade and investment. They worry that defiance will exacerbate tensions and compromise carefully nurtured business relationships. The outcome was the opposite of what Ms. Tsai had expected.

In the latest elections, Ms. Tsai and her candidates campaigned on the need for hanging tough against the mainland. In an exercise in understatement, she acknowledged, “The election results were not as expected.” Resigning “immediately” as party chief, she said “I shoulder all responsibility.” 

That amounts to a confession of error in casting the elections as a vote for her party’s policy toward the mainland. Ms. Tsai has been careful not to support calls for the independence of Taiwan, which remains, in Beijing’s view, a province of China, but she has emphasized the need for building up militarily against the constant threat of invasion.

Communist China’s vastly superior, larger forces are on the mainland, only 90 miles away across the East China Sea. President Biden has sometimes encouraged Ms. Tsai’s hard line against them by stressing America’s “commitment” to defend Taiwan. Yet Washington officially recognizes Beijing as the capital of all China, including Taiwan.

America has no treaty with Taiwan. There are no American bases or troops on the island. Yet a factor in the elections for mayors, county chiefs, and local councils was that voters were actually more concerned about local issues, including Covid, than about relations with the mainland, viewed as a distant threat.

Ironically, Ms. Tsai campaigned on the need to stand strong against China before her campaign for reelection as president in 2020. She won that contest by a wide majority even though the KMT had done well in local elections in 2020. The KMT, it seems, represents traditional sentiments, which might have led to another surprise Saturday. 

That surprise was the rejection of a referendum to lower the voting age from 20 to 18. In another understatement, Ms. Tsai said simply, “There are many areas we must deeply review.”