Along with the right to vote is the duty to vote responsibly, and within that responsibility may be the duty to abstain from voting when you do not see the necessary merit in the candidates. You get my vote if I trust you. If I do not trust you, you do not get my vote. It is as simple as that.
We have an obligation to be concerned, reasonably informed, involved and active in the political sphere, and whether to vote is a serious question for each voter in that involvement.
No commandment of God or of the Church clearly requires voting therefore the moral law does not require it.
The so called "requirement" to vote which some people try to force depends on too many contingents to be an absolute moral requirement. Besides, there are many saints in heaven who presumably do not believe in or care for the democratic system of government with all of its dishonesty.
The only thing that can be insinuated from Christ's teachings is that it is not necessarily immoral to cooperate with the State: render to Caesar is to be interpreted broadly--freedom--to do or not to do. The question in the "render to Caesar" issue ("Is it lawful to give tribute to Caesar, or not?" Mt. 22:17) was not whether is was obligatory to pay tax but whether is was legitimate to pay it, i.e. to participate in the corrupt system: The Lord said it was OK. I too, therefore, hold that it is legitimate to vote and that not voting--abstention--is also a fundamental democratic and Christian right--in conscience.
Upstanding citizens have a right to not vote and a right to criticize, in addition to their right to vote. It's up to them. To force people to vote contradicts the very basis of democracy, viz. by the people!
By the way, the fruits of democracy in Central America the past 200 years have been widespread raping and pillaging and much of it made in USA. Refer to the Kissinger Report for the United States' standing policy regarding Latin America. "Democracy" according to G.K. Chesterton does not exist. It is Oligarchy or Plutocracy, but not Democracy. Whoever has the most power (e.g. the strongest voice, the most money), wins.