Answer:
Age is a demographic factor that has great influence on political opinions.
For example, old people tend to vote for the Republican Party because they tend to be more religious, while young people tend to vote of the Democrats because they tend to be more secular. (Secular means not religious).
Race is another key demographic factor. For example, African americans view on political questions relating to racism are very different from the views that the average white person holds.
Finally, marriage status is also a demographic factor influencing political opinion. Imagine that congress wants to impose a new tax on single people in order to fund a program. Married people would probably be in favour of the measure, or neutral, while most single people would be against it.