Senate Minority Leader Mitch McConnell (R-Ky.) (Molly Riley/AFP/Getty Images)

The Senate Conservatives Fund, a group that often supports opponents of GOP establishment candidates, has endorsed Senate Minority Leader Mitch McConnell's (R-Ky.) primary challenger.

But another key conservative group that often supports insurgent candidates -- the Club for Growth -- on Friday offered some praise for McConnell, while also reserving judgment on the race.