China becomes US political football China has moved to centre stage in the US election, with the Obama administration filing a second trade complaint in as many months against Beijing, in both cases announcing the measures to coincide with presidential trips to the key swing state of Ohio. Mr Obama said the US launched a case against China at the World Trade Organisation over its export subsidies on cars and car parts, alleging they hurt US manufacturers and force them to shift production overseas. In July, also on the eve of a re-election campaign trip to Ohio, the Obama administration took the first step in a formal trade dispute with Beijing at the WTO, challenging Chinese duties on large US cars. The US case was filed on the same day as China launched its own WTO challenge against America, alleging that it was illegally imposing anti-dumping measures on a wide range of its good. "You can talk a good game, or you can play one - and my experience has been waking up every single day doing everything I can to give American workers a fair shot in the global economy," Mr Obama said at a campaign stop in Cincinnati, in south-western Ohio on Monday. "When other countries don't play by the rules, we've done something about it," he added. Mitt Romney has long tried to use China's tightly managed currency to criticise Mr Obama for not supporting American workers, promising to declare Beijing a currency manipulator on the first day of his administration. Mr Obama, and George W. Bush before him, declined to do so, preferring to press China to allow its currency to appreciate, while engaging the country's leaders of broad range of economic and security issues. China's currency has appreciated by 19 per cent over the past five years against the US dollar - and by about 8 per cent since Mr Obama took office in early 2009. "President Obama's credibility on this issue has long since vanished - I will not wait until the last months of my presidency to stand up to China, or do so only when votes are at stake," Mr Romney said. Mr Romney has targeted Mr Obama over his China policies in attack ads tailored for Ohio, a manufacturing state which has battled with competition from Asia for three decades. Mr Obama has defended himself by pointing to trade actions against China, but also by highlighting his bailout of the US car industry of the financial crisis, which left Washington as a major shareholder in companies like GM. At the same time, GM and Ford have enjoyed stellar growth in China over the past decade, mainly by selling into the domestic market, which has now surpassed the US in size. The heart of the Obama administration's latest case lies in persuading the WTO that the Chinese aid offered to producers in certain regions known as "export bases" - violates the prohibition on "export contingent subsidies" that China signed up to when it joined the global trade body more than a decade ago. Michael Dunne, the head of Dunne & Associates, which consults on the Chinese car industry, said the timing of the Obama administration's complaint appeared "highly political." Mr Dunne did not, however, dispute that Chinese industry benefited from subsidies, ranging from preferential access to bank loans, cheap energy and a managed currency which helped exporters. "China's industrial policy remains geared to growth and export targets, whatever it takes," he said. The local and central governments see subsidies not as outside the rules but as investments required to reach official goals. The Obama administration said the Chinese subsidies to the auto and auto parts sector - including grants for research and development, tax preferences and interest rate subsidies - amounted to at least $1bn between 2009 and 2011. This year, as well as the two trade disputes on cars, this year, the Obama administration also launched a challenge against China at the WTO over its exports of rare earth minerals. Between Mr Obama's heightened efforts to fight China at the WTO, and Mr Romney's tough rhetoric, advocates for greater trade liberalisation are growing increasingly worried about the chances of a trade war between the countries. "Instead of pandering on trade with China, both Presidential candidates ought to tout the benefits that come with free trade," said Chris Chocola, head of the Club for Growth, the conservative anti-tax group."Freer trade with countries like China means more markets for American businesses, and more competition leads to lower prices and more choices for American consumers." But Scott Paul, executive director of the Alliance for American Manufacturing, which has been pushing the Obama administration to launch the auto parts case, hailed the action. "President Obama is delivering a major boost to our nation's automotive sector workers and businesses today by holding China accountable for its cheating," Mr Paul said.