If DeMint doesn’t endorse until the primaries are over, then he’s not endorsing period.
Unless you think he’d endorse Obama.
In 2008, Demint endorsed Romney. He has said that he will not endorse Romney this time unless he admits that Romneycare was a mistake. I suspect that he will endorse no one before the SC primary similar to what Steve King did in Iowa. Both may eventually endorse a candidate before the primaries are over.