It could almost be scripted. A U.S. politician threatens to take China on if he makes the White House. The official Chinese press level a barrage of criticism laced with sarcasm. Beijing's Foreign Ministry steps in offering a milder diplomatic response.

Check the calendar, it must be U.S. presidential campaign season again. If things play out as they have in the past, the Chinese will bide their time until the election is over and see who they have to deal with. And if the challenger wins, they can expect a softer line once they actually enter the Oval Office.

This year, however, with the United States in serious financial trouble and the advent of what many call the China century, analysts say there may be more to the exchanges than just a playout of rhetoric.

There are months to go before the real drama unfolds, and the war of words could breed more vocal nationalism on both sides of the Pacific that would have to be closely managed to avoid a serious test of Sino-U.S. relations, they said.

Pressure could come from many directions.

The two powers start this campaign season from much different places. In 2008, China's main focus was ensuring it carried out a successful Olympics and looking inwardly to ensure it held potentially destabilising unrest in check.

Today, a more confident China is the world's second largest economy with a rapidly modernising military, and has seen the United States taken down a peg as it struggles to turn its own economy around. European countries mired in a debt crisis are as likely to head to Beijing as Washington for help.

I think more and more Americans view China as a potential threat, said Sun Zhe, an expert on U.S.-China relations at the Institute of International Studies at Tsinghua University.

From this perspective, next year's election could bring more fierce criticism ... and turn China into a bulls-eye.

Both Washington and Beijing could find it difficult to manage the mutual criticism among the public in both countries and its impact on economic and trade conflict, Sun said.

Hot button issues like an imminent U.S. arms package for Taiwan, the democratic island that China regards as its own, can inflame passions in the unpredictable Chinese blogging community, a key gauge for measuring popular opinion in China.

For Washington, the question is whether voters will link economic woes to complaints that Beijing keeps its yuan currency artificially weak at the expense of American jobs.

BOTH PRESIDENTS CHANGE

In addition, as the United States decides on its president, China will be doing the same, albeit without the popular vote. President Hu Jintao is preparing to hand power to a younger generation of leaders headed by anointed successor Xi Jinping. China would prefer a stable international climate to accompany its desires for domestic tranquility during the transition.

Xi, who has already spent considerable time getting to know U.S. Vice President Joe Biden, is due to become party chief at a Communist Party Congress in the fall of 2012 and president at a parliament session in March 2013.

For the moment, with just over a year to go to the U.S. election, the actors have appeared on cue.

Republican Mitt Romney this month called China a cheater at trade and promised that if he were elected he would slap tariffs on Chinese imports and label Beijing a currency manipulator if it did not quickly move to float its currency.

China's state media shot back, with Xinhua calling Romney's bid to play the China card both absurd and meaningless. The People's Daily overseas edition weighed in, saying it was common for U.S. politicians to summon the clouds with a turn of the hand, and the rain with another, or use trickery and deceit, on the campaign trail.

The Foreign Ministry offered a more diplomatic suggestion that sound China-U.S. relations served the interests of both sides.

It is familiar terrain.

In the 1992 campaign, Bill Clinton criticised President George Bush of for coddling dictators in Beijing and sending envoys to China in the wake of the bloody 1989 crackdown on pro-democracy protests in Tiananmen Square. After election, Clinton charted a course on China similar to Bush, renewing most favored nation status and delinking human rights from trade issues.

Ahead of the 2000 election, challenger George W. Bush took aim at Clinton's description of China as a strategic partner, preferring strategic competitor and tougher trade policies.

Taking a tough stance after assuming office, Bush said he would do whatever it takes to defend Taiwan, angering China. But after the Sept. 11 attacks on New York and Washington, China joined the U.S.-led war on terror and relations began to warm.

Within three years, Bush -- elbow to elbow with Premier Wen Jiabao in the Oval Office -- was warning Taiwan's independence-leaning President Chen Shui-bian not to upset the status quo.

AND AFTER THAT

On the 2008 U.S. campaign trail, challengers took aim at Beijing's currency policy, including then Illinois Senator Barack Obama, who characterised China as neither friend, nor enemy but a competitor. He vowed to be a tough negotiator and to take them to the mat if they were manipulating their currency.

While Obama had a less bellicose campaign approach than his predecessors, his administration has yet to formally declare China a currency manipulator and he again has engaged China.

China's government has become more sophisticated over the years in understanding the U.S. campaign cycle, and now, with its growing global prominence, largely avoids taking the bait.

The Chinese practice is to leave some room for future cooperation. They don't want to make an enemy before the person is even elected, said Jia Qingguo, a U.S.-China relations expert and associate dean of the School of International Studies at Peking University in Beijing.

The Chinese government will feel the pressure (from Chinese public opinion) but unless the U.S. does something that the Chinese government perceives as harming China's so-called core national interests, I think it will exercise restraint in the face of criticism, Jia said.

One issue where China might be forced to respond strongly is the hefty U.S. arms package for Taiwan, Jia said. The Obama administration was expected to formally notify Congress this week of a multi-billion dollar deal including an upgrade for Taiwan's aging fleet of F-16s.

On the U.S. side, Republicans who have traditionally championed free trade and free flows of capital are starting to treat China as a whipping boy, said China expert Kenneth Lieberthal at the Brookings Institution.

It remains to be seen whether Romney's position is simple campaign politics, or a more significant shift on behalf of his backers in the business community who may be demanding a more level playing field in China, a scenario that could add to tension.

If his views reflect theirs, it means that U.S. firms with substantial interests in China have shifted their position in ways that could prove momentous for future relations between the world's two largest economies, William Galston, a senior fellow in governance studies also at Brookings, said in a column.

It also remains unclear if the election trail rhetoric will linger after the confetti has been swept off the stage.

Whether the American leadership will deflect the Republican criticism by taking a more hardline stance toward China has yet to be seen, the People's Daily said.

In the face of this noise, we must be clear-headed, down to earth, and focus on our own development. This is in the long-term interests of the Chinese people.

White house China Barack obama George W. Bush