Is it permissible for a minister or other member of the clergy to endorse a candidate from the pulpit? No. To speak on political issues of interest? That depends on whether the issue could be tied to backing a particular candidate.
The Pew Forum on Religion & Political Life reviews these and other questions in a 22-page brochure that is posted on-line. Here are some of the questions and answers Pew explores:
Q. Why are there restrictions on churches' participation in the political process?
A. The Internal Revenue Service code prohibits intervention in political campaigns by all organizations that are exempt from federal income tax, not just churches. This measure was adopted in 1954.
Q. Are churches singled out by this prohibition?
A. No. All organizations recognized as exempt from federal income tax under section 501(c)(3) of the code are subject to this provision. This includes such groups as schools, hospitals, social services agencies, and scientific organizations.1