HK GOT INT,L STRATEGIC CONSULTING LIMITED

TAIPEI, Taiwan — The president of Taiwan resigned as leader of her party Saturday night after it suffered stunning local election defeats to the opposition Kuomintang, which favors closer ties with China.

The self-ruled island’s political landscape was shaken up by voters who delivered a sharp rebuke to President Tsai Ing-wen’s governing Democratic Progressive Party, or D.P.P., in elections contesting more than 11,000 seats from city mayors to neighborhood wardens. The results of the election, which was seen as a referendum on Ms. Tsai’s first two years in office, have given the Kuomintang a new lease on life and complicated Ms. Tsai’s bid for re-election 14 months from now.

Shortly after it became apparent that the D.P.P. would lose crucial mayoral races, Ms. Tsai resigned her position as party leader, raising the possibility that she would be challenged for her party’s nomination for the presidential election in January 2020.

“As this party’s chair, I take full responsibility for the outcome of today’s local elections,” she said at a hastily assembled news conference at D.P.P. headquarters in Taipei. “People believe in democratic values — today democracy taught us a lesson.”

Opposition Kuomintang mayoral candidates won in Taiwan’s three largest cities — New Taipei City, Taichung and Kaohsiung. The Kaohsiung contest was especially stinging for the D.P.P., which has held the mayor’s office for 20 years and considered the southern city a political stronghold.

Han Kuo-yu, the Kuomintang’s candidate for mayor in Kaohsiung, emerged as the story of the election, defeating his D.P.P. opponent, Chen Chi-mai, who at the outset of the election campaign had been expected to win easily.

“All of Taiwan, all of the ethnic Chinese worldwide, can see the change in Kaohsiung,” Mr. Han said in his victory speech at a large rally. Before the election, he attained celebrity status for his populist and occasionally politically incorrect style. In the final weeks of campaigning, he took that popularity on the road, stumping for Kuomintang candidates around Taiwan, which may have helped decide several close races.

Ko Wen-je, the independent mayor of Taipei and one of the most popular politicians in Taiwan, appears to have barely defeated his Kuomintang opponent, Ting Shou-chung. The close outcome may make Mr. Ko less likely to throw his hat into the ring in the presidential campaign. Mr. Ting has contested the result.

Mayors in Taiwan are similar in stature to governors in the United States, and the Kuomintang mayors offer potential new dialogue partners for Beijing, which refuses to engage with Ms. Tsai and could use them to further isolate her and increase China’s involvement in Taiwan politics.

The Communist Party of China seeks to annex Taiwan, which it has never ruled, and refuses to speak with Ms. Tsai unless she accepts the stance held by her Kuomintang predecessor, Ma Ying-jeou, that Taiwan and China are both part of the same country, with potentially different interpretations of what that country is on either side of the Strait.

China has done all it can to put pressure on Ms. Tsai since she took office in 2016. In the hope of seeing her become Taiwan’s first one-term president, Beijing has poached Taiwan’s diplomatic allies, increased military exercises near its borders and pressured companies to list the self-ruled democracy as a part of China on their websites.

In recent weeks, Taiwanese officials, including Ms. Tsai herself, accused China of trying to influence Taiwan’s election through online misinformation aimed at undermining confidence in the D.P.P. China has rejected the accusations. Taiwan’s Ministry of Justice is also investigating 33 cases of alleged illegal funding of candidates by China, but has not disclosed who is under investigation. Taiwan voters all file paper ballots, which are hand counted so they cannot be hacked.

While China is always a factor, Taiwanese voters also had plenty of local concerns in this election, including stagnant wage growth and severe air pollution in the island’s south.

Several referendum questions concerned same-sex marriage, with voters expressing overwhelming opposition to it. They also supported the removal of gender equity content from school textbooks, which is seen as a major factor behind the strong support for gay rights among Taiwanese youth.

A ruling last year by Taiwan’s constitutional court gave the government until May 2019 to legalize same-sex marriage. The referendum results increased the likelihood that Taiwan will adopt separate civil union status for same-sex couples rather than offering them the same legal status as heterosexual married couples.

A referendum question asking whether the island should be referred to as “Taiwan” rather than “Chinese Taipei” at the Olympic Games and other international sporting events failed to pass after a last-minute push by opponents, including some Taiwanese athletes, who warned that the name change could lead to Taiwan being banned from the Olympics.

Speaking at an election result viewing party in the Wenshan district of Taipei, a Kuomintang volunteer, Lin Mei-chuan, said she disapproved of the Tsai administration’s handling of the economy as well as relations with China.

“People want a change,” Ms. Lin said. “It’s time for someone else to run things.”