"I think if this year, in 2018, if the Nationalists smoothly win Taiwan's city and county elections, that has some warning effects on the party in power, to let them know they've made mistakes in the past two years", said Taipei voter Hong Wei-chi, 40, a marketing specialist.
If President Tsai and her party refuse to change course on China, they risk losing the Presidency and their majority rule in parliament in the 2020 election.
"Having a special marriage law (for gay couples) means we are like second class citizens", he told AFP, adding that having a two-tier system would dent Taiwan's reputation as a trailblazer for equal marriage rights on the global stage. They face both a court order to make same-sex marriage legal by 2019 and elections in 2020.
The complex ballots also included a referendum on a bid to change the name under which Taiwan competes at global sports events that has already angered China.
When asked about the election, a spokesman for Beijing's Taiwan Affairs Office said the results reflected "the strong will of the public in Taiwan in sharing the benefits of... peaceful development across the Taiwan Strait", the official Xinhua news agency reported on Sunday.
The state-run China Daily said Taiwan's people are unhappy the government has not pulled the island out of quasi-economic stagnation and that its policies "have ignored the interests of many groups".
But surveys have consistently shown that Taiwanese people prefer not to have to choose between one or the other; instead they favour the middle ground.
Some voters believe Tsai hasn't done enough to lift Taiwan's economy despite data that points to improvement, said Raymond Wu, managing director of political risk consultancy e-telligence in Taipei.
The elections for mayors and thousands of local posts were seen as a key test for the 2-year-old administration of Tsai, whom Beijing has relentlessly attacked over her refusal to endorse its claim that Taiwan is a part of China.
Some of Tsai's backers attributed the loss to widespread dissatisfaction with her leadership.
Balloons, blankets at frigid Macy's Thanksgiving Day parade
The massive balloon was almost pushed into the sidewalk where hundreds of fans were lined up to watch the parade. They'll be joined by 12 marching bands , 26 floats, and musicians like John Legend , Rita Ora , and Diana Ross .
The KMT, which oversaw an unprecedented thaw with Beijing before Tsai took office in 2016, declared victory in 15 of 22 city and county seats, up from just six going into the election.
To win back support, several analysts said Tsai should move closer to the US, which sells weapons to Taiwan to defend against forceful unification by the mainland. "We have learned a lesson and must reflect on ourselves as, obviously, voters have a higher expectation of us".
The referendum had asked voters if marriage should be defined in Taiwan's Civil Code as being restricted to the union of one man and one woman, as is now the case.
Tsai's domestic reform initiatives, from the island's pension scheme to labor law, have also come under intense voter scrutiny recently.
That has produced a "negative example" for Taiwan in terms of faith in China's promises and enthusiasm for unification with the mainland, Choy said.
"This is a tragic defeat for the DPP", Yao Chia-wen, a senior adviser to the president, told Reuters.
In 2006, Hou became the youngest person in Taiwan's history to head the NPA, and two years later he was appointed president of Central Police University.
Analysts said the USA would not be anxious about the outcome of the elections, as issues of reunification or independence had not played a major role.
Bejing has staged war games around the island of Taiwan and poached five of its diplomatic allies.