Taiwan's fraught relationship with China will be centre stage this weekend as frustrated voters head to the polls to elect a new Beijing-sceptic leader.

The vote comes after eight years of rapprochement between the two bitterly opposed sides, separated since the end of a civil war in 1949, culminating in a historic summit and handshake beamed around the world.

But the landmark meeting between Taiwan's president Ma Ying-jeou and Chinese leader Xi Jinping in November only exacerbated growing fears over Beijing's influence in Taiwan, and voters are pushing back.

Tsai Ing-wen of the traditionally pro-independence main opposition Democratic Progressive Party (DPP) is well ahead in the polls, poised to unseat Ma's Beijing-friendly Kuomintang (KMT).

She has pledged to maintain the current "status quo" with China. But analysts agree a deterioration of ties is inevitable.

"Relations will cool," says Steve Tsang, professor of contemporary Chinese studies at the University of Nottingham.

"Tsai is unlikely to take actions or say things to provoke Beijing -- but Beijing does not trust her."

The thaw under Ma is unprecedented after decades of hostility following Taiwan's split from the mainland at the end of the civil war.

Taiwan has evolved into a boisterous self-ruling democracy, but Beijing still sees the island as a renegade province to be reunited, by force if necessary.

Ma argues his Beijing-friendly strategy has brought stability and peace.

However, there is widespread public wariness over warming relations and anger that resulting trade deals have benefited big business, not ordinary voters.

- Strained relations -

Ties with China were strained under previous DPP president Chen Shui-bian from 2000-2008 due to his staunch pro-independence stance.

Tsai has radically toned down the party's traditionally pro-independence platform.

But Beijing has repeatedly said it will not deal with any leader unless they recognise there is only "one China", the bedrock of closer ties under the KMT.

The concept is at the heart of a tacit agreement between the KMT and Beijing, known as the "1992 consensus", which says there is only "one China" but allows Taiwan its own interpretation.

The DPP does not recognise the "one China" principle or the consensus.

"Adhere to the '1992 consensus' and oppose 'Taiwan independence' is the common political basis for peaceful development of cross-strait relations," a statement issued to AFP by China's Taiwan Affairs Office said.

It added that exchanges could only take place if the consensus and its "core meaning" were recognised.

The Chinese coast across the Taiwan Strait bristles with missiles and Beijing has flexed its military muscles in the past.

In 1996 the United States -- Taiwan's main ally -- sent in the Seventh Fleet after Beijing fired test missiles into the strait ahead of the island's first vote for president.

But observers say both sides have a vested interest in keeping a lid on tensions.

"From China's perspective, it wants to reunite, it wants to increase dialogue," said Yan Jiann-fa, a former head of the DPP's China affairs department, now a professor at Taipei's Chien Hsin University of Science and Technology.

Maintaining stable relations would suit China's President Xi for now, adds Yan, as he battles a slowing economy and implements a widespread corruption crackdown at home.

For Tsai, it is a case of treading the line between public and party scepticism over China ties, and the desire for peaceful relations which the vast majority of the electorate say they want to preserve.

- Communication breakdown? -

There is no official channel of communication between the DPP and Beijing -- but senior DPP officials say that does not mean radio silence.

"They don't interact with the party, but they do interact with people in the party," said Frank Hsieh, who served as Taiwan's premier under former DPP president Chen.

"A lot of Chinese officials also come here under the name of academics," adds Hsieh, a DPP standing committee member.

Hsieh himself made a groundbreaking visit in 2012, meeting with high-ranking officials in Beijing, including State Councillor Dai Bingguo, but in a private unofficial capacity.

However, he acknowledges relations are fragile.

"The Communist Party doesn't trust the DPP so they will have to build mutual trust," he said.

The four months between the election and the new president taking office will be a crucial time for compromise, says Tung Chen-yuan, professor at Taipei's National Chengchi University.

If China decides on a more aggressive stance, it may impose sanctions to up the pressure on Tsai for concessions, says Tung.

"China will want to get some promise from Tsai," he said.

"If she can show some goodwill, then there may be room for dialogue."