Taiwan's ruling party began electing a new chairman on Sunday (Jan 6) - a post vacated by President Tsai Ing-wen after a recent electoral mauling - in a vote closely watched by China and the United States.
Ms Tsai and her Democratic Progressive Party (DPP) won a 2016 landslide, sweeping away a government that had built much closer ties to China over the previous decade.
The result rattled Beijing because Ms Tsai refuses to acknowledge that the self-ruled island is part of "one China".
Beijing cut communication with her administration, stepped up military drills, poached several of Taiwan's dwindling diplomatic allies and started economically pressuring the island.
But in November, Ms Tsai's DPP suffered a string of defeats in local elections, fuelled by a backlash over her domestic reforms and deteriorating ties with China, easily Taiwan's largest market.
Ms Tsai resigned the party chairmanship but stayed on as President.
Analysts say the vote for the new party head will set the tone for the run-up to next year's presidential election.
"It's important because the international community, and China, will be watching," Mr J. Michael Cole, a Taipei-based expert with the University of Nottingham's China Policy Institute, told AFP.
"Any major departure from longstanding policy under President Tsai could alarm international partners and give Beijing ammunition to further crack down on Taiwan."
Voting began on Sunday morning with results expected to be announced in the evening.
China still sees Taiwan as part of its territory to be reunified, despite the two sides being ruled separately since they split in 1949 after a civil war.
While Beijing has reacted frostily to Ms Tsai, she is from a much more moderate wing within her party that favours talks.
She is squeezed between China and more radical members of her own party who favour pushing for independence - something Taiwan has never formally declared.
One of those standing for the chairmanship is Mr You Ying-lung, a polling expert deeply critical of Ms Tsai.
He supported a recent call by four party heavyweights for Ms Tsai not to seek re-election in 2020 - although he said the public should ultimately decide.
"The DPP has to win the power in 2020... right now I can't see how we are going to win in the future," Mr You said in a recent Facebook post.
Mr You's opponent is former cabinet secretary-general Cho Jung-tai, who is backed by leading DPP politicians.
Mr Cho has taken a more conciliatory tone towards Ms Tsai, pledging to promote unity and "restore the confidence" in the party.
Prof Yen Chien-Fa, a political analyst at Chien Hsin University, said whoever comes out on top will have significant influence on the 2020 campaign and whether Ms Tsai is the candidate.
"A chairman who is at odds with Tsai will definitely be a minus (for the party)," he told AFP.
A DPP schism in the run-up to 2020 could favour the Kuomintang, the pro-Beijing party that was turfed out two years ago.
It doubled its seats in November's elections, even defeating the DPP in its traditional stronghold of Kaohsiung.
A DPP swing towards its more radical wing might also worry Washington.
The US remains Taiwan's most powerful military ally but maintains the stance that Taipei must not move close to a formal declaration of independence for fear of stoking a Chinese invasion.
On Wednesday (Jan 2), China's increasingly assertive president Xi Jinping described Taiwan's unification with the mainland as "inevitable", adding that force could be an option if independence was declared.
