They should stick to advocating for issues.
In my eyes it's a clear violation.
We're not talking about churches supporting a candidate, we're talking about individual pastors, in their role as private citizens, who have publically supported Huckabee. If you think pastors should be denied the same right to support the candidate of their choice, simply because of their job, then I think you need to pop open a copy of the Constitution and get to reading.