Tonight, like throughout much of the campaign, there has been a battle to see who is toughest on China. Both Romney and Obama say that China doesn't play by the rules in international trade. Romney says he will declare China a currency manipulator – potentially leading to tariffs – while Obama says he has filed cases against China for unfair trade practices. Obama has declined to declare China a currency manipulator.

The back-and-forth is to be expected. Presidential candidates – including Obama in 2008 -- have long sought to win votes by attacking China as a bogeyman and blaming the country for the United States’ economic woes. There is plenty of evidence that China has not played by the rules, but presidents – including Obama and George W. Bush – tend to take a far more diplomatic line when they’re elected. Obama has filed a large number of trade cases against China, but he has been pretty politic about it.

Romney has promised to go after China on his first day in office, but there’s reason to believe he would hold off. For one, his allies in the corporate community don’t want a trade war with China. Second, there’s not great evidence that declaring China a currency manipulator would lead to more benefits than additional diplomatic pressure.