President Barack Obama launches a campaign swing through the pivotal battleground of Ohio on Monday — armed with a new trade enforcement case against China over allegedly improper subsidies to its auto and auto-parts sectors.

Mitt Romney has recently escalated his attacks on the incumbent as not doing enough to protect America's battered manufacturing sector from unfair competition from Beijing. The message has special resonance in states like Ohio, where the auto-parts sector accounts for a sizeable chunk of the economy. (The White House says the industry directly employs 54,200 Ohioans and supports some 850,000 total jobs).

Obama decided to go after China at the World Trade Organization (WTO) because its subsidies are giving its auto parts a leg up -- even in the U.S. market -- over their American counterparts, the administration says.

The Obama Administration is also escalating another trade enforcement action, begun in July, against what it says are unfair anti-dumping and countervailing duties on some $3.3 billion in U.S. automobile exports to China.

The United States will ask the WTO to set up a dispute settlement panel to consider its case against those duties, which Beijing imposed in December 2011. China acted in response to the auto bailout Obama championed, arguing the rescue amounted to unfair government support for the industry.

"The key principle at stake is that China must play by the rules of the global trading system," an administration official said on condition of anonymity. "When it does not, the Obama Administration will take action to ensure that American businesses and workers are competing on a level playing field."

The Cleveland Plain-Dealer first reported the news.