WASHINGTON (AP) — The United States launched a trade complaint Thursday against China at the World Trade Organization, accusing Beijing of unfairly imposing duties on more than $3 billion in exports of American-produced automobiles.

The announcement came as President Barack Obama hit the campaign trail in the battleground state of Ohio, where automakers have been affected by the tariffs imposed in December. It underscored how America’s trade relations with rising economic power China could color the political debate ahead of the November presidential election.