I just read this on the Rachel Maddow site (not a big fan, but it came on my FB page via a friend link): Remember that time President Obama raised the minimum wage for federal contract workers and Republicans freaked out but then nothing bad happened (not even socialism!)?
The federal government can do whatever they want. They can just print more money or raise taxes to pay for it. Private businesses, in different States, with different costs of living , is what concerns many.