HONG KONG — Voters in Taiwan are widely expected to deliver a victory on Saturday to President Tsai Ing-wen, in defiance of China’s pressure campaign against the island democracy.

If she wins a second term, as polls indicate she will, Ms. Tsai will have made a dramatic comeback from 2018, when her party was battered in local elections. In the 14 months since, she has rallied her party’s leadership behind her and rebuilt public support by overseeing economic growth, despite Beijing’s efforts to isolate her government.

Ms. Tsai’s rise has been driven in part by concerns about Chinese encroachment. Xi Jinping, China’s leader, has lured away some of the few countries that formally recognize Taiwan, as well as stepping up military air patrols and sending carriers through the Taiwan Strait.

But according to surveys, voters believe Ms. Tsai is better able to defend Taiwan’s sovereignty than her challengers. The issue took on increased importance last year as Hong Kong saw huge protests against China’s increasing sway over that city.