100% of all voters are committed to vote one way or the other in accordance with their interests as they perceive them, and those interests are family, social, economic, religious affiliation, part of the country ~
Change is slow, but with single member district voting, we end up with just two large parties. You have to have 50%+1 to win. All those dissatisfied with the results of a large winning party may gravitate to the other large party to help it win more often.
These two large parties are surrounded by a thin fringe of political interests ~ which rarely win anything.
One reason the Democrat party has more affiliations than the Republicans is simply that they used to win far more races than the Republicans. As time has changed and Democrats have tired of losing, they have moved to the Republican label, but usually as part of a broader affiliation ~ e.g. geography, religion, social, etc.
Ergo, white Southerners became Republicans and began winning again. Black Southerners became Democrats and won almost all the mayorality and city council positions in the Souf'.
That's very positive feed back for both groups ~ after all, in politics WINNING IS THE ONLY THING.
That would mean that 100% are more influenced by logic and principle than by more superficial concerns.
The American Idol type voters, the Emotional voters, and the Blue Jay Shiny Object voters are influenced by external manipulation rather than logic. They are the swing voters, and election results rest on their capricious voting behavior. They may call themselves Republican, Democrat or Independent, but what they have in common is that they are influenced by form over substance (e.g. - "Vote for the Cool Black Guy").