BEIJING - With the opening of a hotline came the drawing of a red line.

On Wednesday, China announced that a new hotline had been inaugurated with Taiwan in an effort to build trust between the longtime rivals, and maintain the peace across the narrow strait that divides them.

But at the same time, Beijing warned the island that it still considers a renegade province that rough seas could lie ahead after next month's presidential elections.

Unless the winner of those elections explicitly endorses the idea that China and Taiwan are one country, the entire dialogue process between the two sides "will inevitably be affected and could even collapse," a senior official in Beijing warned.

"The ship of cross-strait peaceful development will encounter terrifying waves or could even capsize," Ma Xiaogang, spokesman for the mainland's Taiwan Affairs Office told a news conference.

The "one China" principle, agreed in 1992, allows both sides to claim to be rightful rulers of the Chinese nation, but explicitly closes the door to the idea that Taiwan could one day become an independent nation, a concept that is anathema to Beijing.

The 1992 consensus, as it is known, was agreed between China's Communist Party and Taiwan's Nationalist Party, or Kuomintang, and has underpinned a deepening of trade and diplomatic ties between the two sides, culminating in a historic meeting of the two sides' presidents in November.

At that meeting, both sides took pains to stress the summit had only been possible because of the 1992 consensus. That was seen as a preelection message to Taiwanese voters, and to the opposition and more independence-minded Democratic People's Party (DPP), which has never endorsed the "one China" idea.

DPP candidate Tsai Ing-wen is the overwhelming favorite to win the Jan. 16 presidential election. She supports maintaining the status quo with Beijing, and even deepening trade ties. But pressed by her main opponent, Eric Chu of Kuomintang (KMT), at a televised debate Sunday, she again declined to endorse the "one China" idea, while stressing the importance of a rational dialogue.

"As long we have sincere communication, I believe cross-strait relations can be stable," Tsai said, according to Bloomberg. "The 1992 consensus is one option, but it's not the only option. It is inappropriate to continue to frame it as such."

Tsai has held talks with "persons of influence in Beijing," and is likely to have already explored some of those other options, said J. Michael Cole, a senior Taipei-based fellow at Nottingham University's China Policy Institute.