Not only is ideology used to manipulate people, it is one of the most efficient ways to do it. Ideology and religion have similar characteristics: they entrap their adherents to package deals of knowledge. Once they've concluded that the same person who hates abortions must also approve of lower taxes (as if the two issues combined make any sense at all) they can easily group people together or apart. Because these ideas lumped together make no sense, the people that believe in the ideas as lumped together must also dump logic (to at least some extent). Thus, manipulation can work.
Humans are social animals. They'll go out of their way to be friendly to strangers and will keep their family structure their whole life. Because of the need for approval by others, they will conform to others' values. It is easy to notice a person's political tendencies by what family they grow up with, and socio-economic demographics will even give people absolute answers to their tendencies. With both sides claiming morality, neither could ever be wrong as long as the family and neighborhood approves of those ideas.
Economic culture will factor in. This moves states to act in accordance with political theory. So long as a state's economy has a vocal forefront, their leaders will move the state's ideology toward fulfilling that economic component. The politician who campaigns on corn wins Iowa, the politician who campaigns on cars wins Michigan, the politician who campaigns church-attendance will win South Carolina, ect. These first primary states are stupidly easy to win for the best politician. This is why California, with such a diverse economy is put on the side burner until the gimme-states are won. Hell, everyone wants to keep their jobs and wants to be noticed. The politicians understand how important holding up a mirror is. What isn't shown is the ugly, violent, sociopath who holds the mirror.
The final factor is the news media. The news media makes damned sure that people will only have two choices and two voices; those who suggest anything beyond the narrow American political spectrum are labeled extremists. After an election, the news will describe the political decision of voting. They will say "America has changed". Though it has not, the goal of the news is to give its viewers a sense of validation to ease buyers remorse. Since politics is such an emotional investment, the news plays the role of the salesman after a purchase to tell the people "it's okay, you're doing the right thing".
This process is an interesting one, it's like raping a woman and convincing her afterward she wanted to be raped. After convincing her, there's no need for the rapist to worry about going to prison. After all, she had a choice to be raped in the same way people can choose their government.