Any candidate for political office cannot have any type of regular show/program without their opponent(s) receiving equal time and or agreeing to allowing them to continue to have their show. In the event that Huckabee would run for office, he most certainly would give up his daily report (can't see Citadel giving his opponents equal time - or for that matter, any of them agreeing to let him remain on the air.
A similar situation occurred a few years ago in Houston when Dan Patrick (the politician and majority owner of KSEV AM 700) was running for his first term; Patrick was able to get his opponent to agree to allow him to remain on the air while seeking office. However, this is rather unusual, to say the least, and if we're talking about national politics, I just can't see it happening.