The battle for Senate Republican Leader starts now. Other than that, DeMint's endorsement makes no difference. He consecrated Rand Paul with kind words back in February, so his preference in Kentucky's primary was about as much of a secret as McConnell's. Nonetheless, just days ago DeMint said he had not taken the step of endorsing Paul because he didn't want to poke a finger in McConnell's eye. DeMint said he'd intervene if the race got "unfair."
The race has gotten plenty unfair. Sen. Jim Bunning encourages Trey Grayson to run and then endorses Rand Paul. Dr. James Dobson endorses Trey Grayson (who is indisputably pro-life) and then does an about-face to endorse Rand Paul. Like the DeMint endorsement, the Bunning and Dobson endorsements were not so much about supporting Paul as punishing McConnell.
The only Kentuckians who could care less about DeMint's favorite are already in the Paul cult.