TAIPEI, Taiwan (AP) — Taiwan’s two main opposition parties, both of which have vowed to restart talks with China, announced a joint presidential ticket for January’s election in a deal that could bring a major political upset in the self-ruled island democracy.

The agreement would bring together Hou Yu-ih, the presidential candidate for the Kuomintang, one of Taiwan’s two major political parties, and Ko Wen-je, of the independent Taiwan People’s Party.

Up until now, both Hou and Ko have trailed in polls behind frontrunner William Lai, the Democratic Progressive Party’s candidate who currently serves as vice president.

Lai and incumbent President Tsai Ing-wen have both been criticized by Beijing as separatists who should be blamed in the event a war erupts across the Taiwan Strait. China considers Taiwan as part of its territory and has not renounced the use of force to take control over it.

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The Kuomintang, also known as KMT, has had a friendlier relationship with Beijing during former President Ma Ying-jeou’s two terms, between 2008 and 2016.

The KMT maintains better communication with China is necessary to avoid a conflict. Meanwhile, the DPP’s line of argument is that Taiwan does not seek to separate itself from China because it is already an independent country.

Ma on Wednesday hosted a meeting between Hou and Ko at which the two candidates agreed to use opinion polls conducted between Nov. 7-17 to determine the makeup of their presidential ticket, with the result to be announced on Saturday.

Hou said he and Ko’s teams have “put aside their personal interests and moved forward” for a “common ideal, for the security of the country, and the well-being of the people.”

Ko, meanwhile, called on the two parties to work together so “we can move forward.”

Some polls have shown that if Hou and Ko were to team up, regardless of who would be the presidential candidate and the running mate, they could beat Lai, who is expected to run alongside Hsiao Bi-khim, Taiwan’s representative to the United States. The DPP has yet to confirm Hsiao as Lai’s running mate.

A fourth candidate, Terry Gou, the billionaire founder of tech giant Foxconn, is also running for president.