Click here to watch "Meghan."

The Service Employees International Union is putting nearly a half million dollars behind an ad -- running in Ohio only -- that criticizes John McCain for supporting policies that it says resulted in American jobs going overseas.

"Meghan" (subscription), started running in this pivotal battleground state Thursday. The spot features Meghan Cofield, a Dayton factor worker who saw her job move to China. The group chides McCain for supporting the North American Free Trade Act, which the SEIU asserts allows companies to receive tax benefits for exporting jobs overseas.

While both candidates have led in Ohio over the last several months, the latest polling data compiled from Pollster.com shows Barack Obama's numbers going up while McCain's trending downward.