If we are not preaching politics from the pulpit we are not preaching the gospel. Jesus BEGAN his ministry by declaring that he came to bring the gospel/good news to the poor; to declare release to those imprisoned; to offer sight to those who do not see; to free the oppressed and to proclaim the jubilee — the year of restoring the equitable distribution of wealth (Luke 4: 18-19).
We should not be PARTISAN from the pulpit. We should not endorse specific candidates or parties. But it is our duty to talk about moral values and assess what moral values are reflected in our political choices. Political in the classic meaning of having to do with the polis — the city or community. We cannot avoid political preaching. It's just a matter of what values we are communicating in our preaching.