Here's your chance, but I don't suggest you do it.
PG has pointed me to a test case where the Alliance Defense Fund, basically a conservative ACLU, is encouraging ministers to endorse political candidates on Sunday, September 28, 2008.
I'm pretty extreme on church state issues partially as a moral thing and partially for strategic reasons in that I'm a liberal and I think conservatives are just plain better at using religion in the ways that currently endanger one's tax exempt status. (At least partially because some liberals have moral issues with it.)
As it stands, lay services get out of hand sometimes, but mostly ministers are reduced to hinting that there's a party of decent folks and a party of greedy bastards and leaving the congregation to figure out which one is which. (I've been in the pews when this was said. I'm paraphrasing, but not much.)
A few reasons why I hate this: I don't want to hear any more about politics in church than I have to. I don't want the candidates to have to pander to religion any more than they have to. I don't want candidates feeling that they need to suck up to ministers and I don't want ministers tempted with the sort of earthly power that asskissing politicians would be offering.
It's comforting that I really don't think the ADL's attempt is going to survive the courts. As recently as 2000, three Reagan appointees on a federal appeals court shot down a New York church's attempt to buy advertising against a candidate.
To me, the answer is simple. If churches want to preach about politics, they should just suck it up and pay taxes. (And if my church did that, I would find a different church much as I would if my minister started endorsing a brand of sneakers or anything else.)
This also gives a good test. The question I am most commonly asked about this stance is "Is it possible for there to be a moral issue or candidate so crucial to people of faith that it is worth the violation of church and state to speak out for/against it?"
The tax question provides a simple answer. If the issue is so crucial that it is worth giving up your 501(c)3 status, then give it up and you won't hear one word of complaint from me, except as the door hits me in the ass on the way out if this happens at my congregation.
If the issue isn't worth giving up a chunk of money for, well, you have your answer on how truly crucial it is, don't you?
CLARIFICATION: I'm 90 percent sure that this is obvious and Robin is teasing me in the comments but just in case: I am only interested in endorsements FROM THE PULPIT. Ministers may endorse whatever brands of sneaker and politician they like in their own private lives.