President Obama kicked off the week in the battleground state of Ohio, where he spent much of the time Monday talking about China.
His administration filed a new trade complaint against China with the World Trade Organization on Monday. The White House is challenging Chinese subsidies for auto parts.
Republican Mitt Romney's campaign has been criticizing the administration for not taking a tougher line against Chinese trade practices. Romney dismissed the new trade complaint as "too little, too late."
Getting tough on China has been part of Romney's stump speech from the beginning. But last week, speaking in Northern Virginia, he went into more depth than usual. It was the first rally after his contentious press conference about Libya, and he turned his attention to China.
Not only did he promise to label China a "currency manipulator" on his first day in office. Romney also accused China of stealing American technology and intellectual property.
"Did you know they even have an Apple store?" Romney said at a rally. "It's a fake Apple store; they sell counterfeit Apple products. This is wrong. We're gonna crack down on China when they manipulate their currency, when they steal our goods, when they don't protect our intellectual property. We're gonna make sure that China understands we mean business. Trade is gonna work for us, not just for them."
On his weekly podcast, he hit the same theme, saying, "In 2008, candidate Obama promised to take China to the mat. But since then he's let China run all over us."
And the Romney campaign released an ad accusing Obama of letting American jobs slip away to China.
The U.S. has lost manufacturing jobs since Obama took office. But since 2010, manufacturing has grown steadily in the U.S., one of the few bright spots in this economy.
The Obama campaign released an ad of its own late last week accusing the Romney team of hypocrisy, saying: "Romney's never stood up to China. All he's done is send them our jobs."
Democrats point out that Romney has profited from Chinese companies, both during his work in the private sector at Bain Capital and in investments he has maintained since he left the firm. A U.S. court found at least one of the companies Romney profited from was guilty of copying patented technologies.
In the middle of this tug of war, the Chinese weighed in. China's state run Xinhua news agency published an editorial saying that Romney could ignite a trade war if he follows through on his rhetoric.
When the Obama campaign called attention to the column in Xinhua, Republicans accused the Democrats of citing communist propaganda.
Christopher Johnson, a China expert at the Center for Strategic and International Studies, says the Chinese expect harsh rhetoric during a presidential campaign, but they're a little bewildered by what they're hearing from Romney.
"Traditionally they tend to favor the Republican Party, and yet Gov. Romney is being pretty tough on them, which is difficult for them to understand, again, especially because they felt they had a relationship with him from the past," Johnson says.
Johnson points out that China has a new incoming president — Xi Jinping. He's under pressure to prove that he's not soft on the United States, just as Romney is under pressure to show that he's tough on China.
If and when both men act on that pressure, it could start a new chapter in the already tense relationship between the world's two largest economies.