Cheney's endorsement today is the highest-level public endorsement so far in the June 8 GOP primary race to replace term-limited Republican Gov. Mark Sanford.
In his endorsement, Cheney calls Barrett one of the most conservative leaders he's worked with. He also praises Barrett for his support of a bailout of banks and Wall Street institutions that's become hugely unpopular this election year.
Also today, Barrett rolled out a 60-second campaign ad aimed at underscoring his decision to support a bailout that he says hasn't been implemented well.
Other big endorsements in the primary include Alaska Gov. Sarah Palin backing state Rep. Nikki Haley.