Taiwan President Tsai Ing-wen attends a ceremony to sign up for Democratic Progressive Party's 2020 presidential candidate nomination in Taipei, Taiwan. File photo/ Reuters

Taiwan’s pro-independence ruling party took a major step on Thursday toward nominating incumbent President Tsai Ing-wen - a thorn in the side of China - as its candidate for a second presidential term.

The Democratic Progressive Party announced that Tsai had won a primary over challenger William Lai, a former premier, in three days of polling. Her nomination is all but sure to be ratified by the party next week.

Tsai received approval from 35.7% of the roughly 15,000 people polled, and Lai got approval from 27.5%, party Chairman Cho Jung-tai told a news conference.

She would face a candidate from the opposition Nationalist Party in the January election.

Tsai, first elected in 2016, fell in opinion polls last year as Taiwanese worried about inaction toward China and stubborn domestic economic issues such as jobs and housing prices.

But she has gained momentum this year by hitting out at China over the Communist leadership’s insistence that it someday take control of Taiwan. The self-governing island split from China seven decades ago.

Chinese President Xi Jinping said in January that Taiwan should be ruled like Hong Kong, which is in the thick of street protests targeting Chinese control. Hong Kong is part of China, but has a measure of local autonomy.

Tsai’s Democratic Progressive Party embraces more autonomy for Taiwan rather than a tie-up with China.

The Nationalist Party advocates closer relations with Beijing. When it controlled the presidency from 2000 to 2008, the two sides signed more than 20 agreements covering trade, investment and transportation.