MOUNT HOLLY, N.C. – Mixing politics with policy, President Obama returned to North Carolina on Wednesday to seek support in this key election-year swing state and to propose new federal incentives to spur “clean energy” vehicles.

In a spirited speech at the Daimler Trucks manufacturing plant — a rare union shop in right-to-work North Carolina — Obama announced a $1 billion challenge to communities that, he said, could eventually reduce oil dependence.

Those willing to shift to more energy-efficient vehicles, the president said, would be rewarded with bigger tax breaks of up to $10,000 as well as other federal assistance.

The plant in Gaston County’s second largest city not only manufactures diesel trucks, but also hybrid and natural gas versions. Last November, it became the first company to deliver its 1,000th natural gas truck.