Often times people say when it comes to voting "I look at each candidate and vote for the best one." To myself, this is like going to the Packers-Bears game and cheering for Brett Favre and Brian Urlacher. Why not? They are both the best players out there. No, the smart person cheers for the Packers (If you do not cheer for the Packers note closely that last comment) all the time. Politics is the same way.
Of course the problem most people will bring up is there are only two teams and neither team exactly matches my beliefs. We could put fifty teams onto the field and none of them will exactly match your beliefs. Yes, you will probably find one closer to your beliefs but this is not
the reality. The reality is there are two competitive political parties in our system of government. The only political party that could satisfy that demand would be a political party made up of one person, yourself.
This most conspiratorial types would have you believe is because the two dominant parties have rigged the system in their favor. This is something I believe to be totally at odds with history and it is the nature of our system that molds two dominant parties out of many. Remember our motto Epluibus Enum. The idea is to pick the party that is most closely aligned to your beliefs and support that party and if you do not like a position in your party of choice then work to affect change or accept the difference, you may not like a colleague on a project team you are on at work, but you accept you have live and work with that person.
The next usual objection is "I like some of the ideas from the Republicans and some from the Democrats." This admittedly withstands criticism a little better than the previous ones mentioned. Though, I find people generally when confronted with more than a surface
understanding of the ideas behind the party's stands on issues will generally come to a more consistent viewpoint. There are ideological strings that connect even what seem to be the most unrelated issues and ideas, and when people start to see what those strings are, they usually prefer one string over the other.