Having pledged last month to back a plan for nation-wide emissions standards for the car industry, presumptive U.S. presidential nominee John McCain today reversed his stance when he told a group gathered for a town hall meeting that he supports individual state-set emissions standards.

Choosing to make such a statement in front of a room full of General Motors engineers is an odd thing to do.

The carmakers have been among the most vocal proponents of a national emissions scheme, arguing that compliance with a patchwork of state-by-state programs inflates costs into the billions of dollars. A single, coherent standard would be more manageable, they say.

Nevertheless, the statement made by McCain is clear in its intent, if somewhat soft in its formation. "I guess at the end of the day, I support the states being able to do that," indicating the independent determination of state-by-state emissions standards, reports The Detroit News. The new stance is one that favors States' rights, a position not incongruent with much of the rest of McCain's ideological platform, but in direct opposition to his pledge of overriding federal standards.

The issue has come to a head in recent months with California's suit against the Environmental Protection Agency (EPA) for the right to set its own, more restrictive, emissions standards. Already BMW is converting 500 Minis to electric power to comply with the state's zero emissions vehicle requirement, and more makers are expected to follow.