Yes, Christian pastors are required to preach on politicial issues, because it is important to meet the needs of the whole Christian, which includes the role of the Christian in society.
Politics involves everyone, whether they like it or not, so it is absolutely required that Christian preachers discuss Christianity and its role and function in politics and society.
It is necessary for Christian pastors to provide guidance for church members on how to follow the Bible when they vote or function as citizens in countries, becuase as disciples of Christ, God’s Word should guide their heart and mind.
When pastors ignore politics and elections during Sunday sermon, such pastors are being negligent and rejecting the duty that God requires of them.
Standard of Care owed by Christian pastors for church members is specific directions from the Holy Bible on how to think about and act on current politicial issues of the day. Glory should be given to God!