St. Charles Borromeo Church web site]:
First of all, voting is a duty and a serious responsibility.
2442 It is not the role of the Pastors of the Church to intervene directly in the political structuring and organization of social life. This task is part of the vocation of the lay faithful, acting on their own initiative with their fellow citizens. Social action can assume various concrete forms. It should always have the common good in view and be in conformity with the message of the Gospel and the teaching of the Church. It is the role of the laity "to animate temporal realities with Christian commitment, by which they show that they are witnesses and agents of peace and justice."231
Secondly you need to consider the candidates:
2237 Political authorities are obliged to respect the fundamental rights of the human person. They will dispense justice humanely by respecting the rights of everyone, especially of families and the disadvantaged.
Specifically with regards to "non-negotiables," such as respect for the dignity of human life:
2273 The inalienable right to life of every innocent human individual is a constitutive element of a civil society and its legislation:
"The inalienable rights of the person must be recognized and respected by civil society and the political authority. These human rights depend neither on single individuals nor on parents; nor do they represent a concession made by society and the state; they belong to human nature and are inherent in the person by virtue of the creative act from which the person took his origin. Among such fundamental rights one should mention in this regard every human being's right to life and physical integrity from the moment of conception until death."80"The moment a positive law deprives a category of human beings of the protection which civil legislation ought to accord them, the state is denying the equality of all before the law. When the state does not place its power at the service of the rights of each citizen, and in particular of the more vulnerable, the very foundations of a state based on law are undermined. . . . As a consequence of the respect and protection which must be ensured for the unborn child from the moment of conception, the law must provide appropriate penal sanctions for every deliberate violation of the child's rights."81
2275 "One must hold as licit procedures carried out on the human embryo which respect the life and integrity of the embryo and do not involve disproportionate risks for it, but are directed toward its healing the improvement of its condition of health, or its individual survival."83"It is immoral to produce human embryos intended for exploitation as disposable biological material."84"Certain attempts to influence chromosomic or genetic inheritance are not therapeutic but are aimed at producing human beings selected according to sex or other predetermined qualities. Such manipulations are contrary to the personal dignity of the human being and his integrity and identity"85 which are unique and unrepeatable.
2276 Those whose lives are diminished or weakened deserve special respect. Sick or handicapped persons should be helped to lead lives as normal as possible.
2277 Whatever its motives and means, direct euthanasia consists in putting an end to the lives of handicapped, sick, or dying persons. It is morally unacceptable....and respect for human sexuality:
Thus an act or omission which, of itself or by intention, causes death in order to eliminate suffering constitutes a murder gravely contrary to the dignity of the human person and to the respect due to the living God, his Creator. The error of judgment into which one can fall in good faith does not change the nature of this murderous act, which must always be forbidden and excluded.
2335 Each of the two sexes is an image of the power and tenderness of God, with equal dignity though in a different way. The union of man and woman in marriage is a way of imitating in the flesh the Creator's generosity and fecundity: "Therefore a man leaves his father and his mother and cleaves to his wife, and they become one flesh."121 All human generations proceed from this union.122
2360 Sexuality is ordered to the conjugal love of man and woman. In marriage the physical intimacy of the spouses becomes a sign and pledge of spiritual communion. Marriage bonds between baptized persons are sanctified by the sacrament.
A candidate who does not respect these basics of human dignity does not deserve to serve in office. Remember:
2244 Every institution is inspired, at least implicitly, by a vision of man and his destiny, from which it derives the point of reference for its judgment, its hierarchy of values, its line of conduct. Most societies have formed their institutions in the recognition of a certain preeminence of man over things. Only the divinely revealed religion has clearly recognized man's origin and destiny in God, the Creator and Redeemer. The Church invites political authorities to measure their judgments and decisions against this inspired truth about God and man:
Societies not recognizing this vision or rejecting it in the name of their independence from God are brought to seek their criteria and goal in themselves or to borrow them from some ideology. Since they do not admit that one can defend an objective criterion of good and evil, they arrogate to themselves an explicit or implicit totalitarian power over man and his destiny, as history shows.51
Assuming you can't distinguish candidates on life issues, look at how they voted on things like the first amendment (religious liberty, free speech), the second amendment (right to self defense), the fourth amendment (right to privacy) and other aspect of our constitution. Are they restricting or threatening our rights?
Being an informed voter isn't hard. With the internet it's easy to see the voting record of incumbents on various issues, and to read the platform of each candidate. Do a little research today, and vote your conscience on Tuesday.
2238 Those subject to authority should regard those in authority as representatives of God, who has made them stewards of his gifts:43 "Be subject for the Lord's sake to every human institution. . . . Live as free men, yet without using your freedom as a pretext for evil; but live as servants of God."44 Their loyal collaboration includes the right, and at times the duty, to voice their just criticisms of that which seems harmful to the dignity of persons and to the good of the community.