The challenge by Chen Shui-bian and his Democratic Progressive Party (DPP) shatters this cosy consensus. Now Taiwan could be the base for the democracy movement mainland leaders fear. And what will mainland Chinese think about democracy if Mr Chen runs Taiwan so well that it marches ahead of them? With no other party able to play a role, the CCP did nothing during Taiwan's massive arms build-up of the 1960s and 70s. The only serious military attack was in 1958 when Quemoy island was bombarded because Mao Zedong believed the Great Leap Forward had given him economic strength. When the mainland teetered on the edge of collapse, the attack stopped.

The next attack took place with the missile tests in 1995 and 1996 when the KMT permitted the first openly fought elections for the Legislative Assembly and the presidency.

So although a generation of mainlanders had been taught that it was the People Liberation Army's duty to liberate the Taiwanese from KMT oppression, the PLA did nothing until the Taiwanese had a chance to choose their own leaders.

As long as the KMT was as ruthless in imprisoning critics as was the CCP, military endeavours by the PLA were directed against Vietnam, Cambodia, India and above all the Soviet Union, which kept a massive nuclear armed force on the border.

Since President Jiang Zemin, National People's Congress chairman Li Peng and Premier Zhu Rongji are in power due to the successful suppression of democracy inside and outside the CCP in 1989, they clearly cannot now stand by and watch a democracy flourish in Taiwan.

The current leadership has strived to block any political liberalisation on the mainland. Even some reforms of the 80s have been reversed. The system of people's congresses, for instance, is now more firmly under the grip of the party than ever before. If a thriving and dynamic democracy is allowed to flourish anywhere in the Chinese world, then no-one in Zhongnanhai can sleep easily.

In the 90s, the CCP fought hard to prevent a fully fledged democracy emerging in Hong Kong. Just as many Communist leaders once feared Hong Kong could become a base and an inspiration for a mainland democracy movement, Beijing fears Taiwan could fulfil the same role if its democracy flourishes.

A DPP-run government means that the CCP can no longer claim that the elections are just an empty propaganda show. The absence of any reports on the elections in Saturday's mainland press speaks volumes about the uncertainty of how to report it.

The Communist Party has avoided directly intervening in Taiwan's internal politics, such as by distributing party donations as it did in the United States. In turn, the Taiwanese elite has avoided doing more than offering verbal support for dissidents from the mainland, such as Wei Jingsheng.

Mr Zhu's effort on Wednesday to sway voters in Taiwan set a precedent. Now or in the future, Mr Chen or someone else may decide that two can play that game. Some wealthy Taiwanese might want to provide funds, training, broadcasting facilities and political asylum for mainlanders struggling to bring about change, especially if that is essential for the survival of Taiwan's newly won freedoms.

The CCP narrowly avoided such a situation in Hong Kong after Tiananmen when many people, including leading tycoons, were tempted to bankroll an opposition movement. Instead Deng Xiaoping opened up the mainland to fresh investment. These same tycoons saw so many opportunities to make money that they preferred partnerships with the scions of top Communist families.

A similar tactic has been tried with Taiwanese industrialists who, lured with special concessions, have been pouring money into the mainland. Their investments make them hostages to Beijing and they are among the loudest voices speaking in favour of appeasing the mainland.

Yet compared with Hong Kong, where a few giant conglomerates exert enormous influence, most Taiwanese companies are small and family-run.

Whatever happens, this presidential election campaign has changed Beijing's thinking. Only this week, it seems, has it dawned on the Chinese leadership that the Taiwanese electorate may really be free to exercise its will with unpredictable consequences.

It had been widely assumed in Beijing that the KMT's lifting of martial law in 1987 and release of political prisoners was a ploy to strengthen support for Taiwan in the US, rather than a move towards true democracy. This also helped diminish President Lee Teng-hui's achievements in the eyes of many mainland observers. Yet he has transformed the ugly dictatorship of Soviet-trained Chiang Ching-kuo, which existed just 12 years ago, and led one of the two parties which controlled China's modern state to abandon the common heritage.

It is often forgotten that before the KMT and the CCP plunged China into a never-ending civil war, the country was heading in quite a different direction. Voters in the first Chinese elections in 1909 (before the fall of the Qing dynasty), selected representatives to provincial assemblies which in turn chose delegates to the National Assembly.

In 1912 and 1913, there were fresh elections for a parliament divided into a Senate and a House of Representatives. Then, in 1918, the franchise was further extended and voters elected a parliament which lasted until 1923. Four years later, the CCP and the KMT had passed laws so their leaders could execute anyone found guilty of 'counter-revolutionary crimes'. They began a brutal fight to establish a one-party state and it is only now that Taiwan at least has a chance to escape from this tragic history.

Jasper Becker is the Post's Beijing bureau chief