You have to make up your own mind using a well-formed conscience and a mature understanding of the teachings of the faith while also taking the time to understand candidates, issues and current realities.
For instance, consider candidates whose public lives and public work most fully embrace the core principles of the Church’s teachings. They should, by word and deed, exhibit a respect for human life and dignity, honor the principle of subsidiarity, strive to contribute to the common good and understand that those in service to others must embrace God’s call to love our neighbors as ourselves.
It is not the Church’s task to set forth specific political solutions – and even less to propose a single solution as the acceptable one – to temporal questions that God has left to the free and responsible judgment of each person. It is, however, the Church’s right and duty to provide a moral judgment on temporal matters when this is required by faith or the moral law.” (Doctrinal Note on some questions regarding The Participation of Catholics in Political Life, Congregation for the Doctrine of the Faith)