TAIPEI •A potential joint bid for Taiwan’s presidency by the island’s two main opposition parties was in disarray on Saturday as they bickered on how to agree on who will run for president with time running out to make a decision.

The issue of China, which views Taiwan as its territory, looms over the Jan. 13 parliamentary and presidential elections. China has stepped up military and political pressure, including high-profile war games, to press the island to accept its sovereignty claim, which Taiwan rejects.

After weeks of sometimes acrimonious talks on joining up for the presidential election, the Kuomintang and the much smaller Taiwan People’s Party agreed on Wednesday to look at an aggregate of opinion polls to decide which party’s candidate would run as president and which as vice president.

But both parties failed to reach agreement on how to interpret opinion polls and thus decide who will stand for what position by an originally scheduled deadline of Saturday. Candidates have to register with the election commission by Friday.

The ruling Democratic Progressive Party’s (DPP) candidate, Vice President Lai Ching-te, has for months led most opinion polls to be Taiwan’s next president, leaving the KMT’s Hou Yu-ih and the TPP’s Ko Wen-je to battle it out for second place.

China detests front-runner Lai, regarding him as a separatist, and has rebuffed repeated calls from him for talks. Hou especially has vowed to renew dialogue with Beijing, and says Lai is a dangerous supporter of Taiwan independence.

Some opinion polls have shown that if Hou and Ko teamed up, in whatever combination, they would beat Lai and his presumptive running mate, Hsiao Bi-khim, Taiwan’s envoy to the United States.

Former Taipei mayor Ko, who has previously said the things he hates most are “mosquitoes, cockroaches and the KMT,” asked by reporters whether talks had now broken down said anything was possible before Friday but he could not be expected to “surrender” to the KMT on the poll issue.