Pastor's Rights to Endorse Candidates

I have been hearing a lot of conversations recently about how Christian Pastors have no business endorsing, or giving opinions of, political candidates behind the pulpit. This argument is made because the Church is tax exempt.
One, although churches are typically tax exempt, most pastors are not. We pay a whopping 33% in taxes to Uncle Sam because we are considered "self employed".
Two, men of God have a history of standing up to government. Read about John the Baptist in Mathew 14. Not only do pastors have a right, but also an obligation, to guide the people they serve.