Politicians always say that they listen to the voters, but if you want to find out how a certain population will vote, it's better to have a linguistics expert listen instead.
American linguist William Labov of the University of Pennsylvania, noted that voting patterns and political ideology are often demarcated by the "red versus blue" accents:
Labov points out that the residents of the Inland North [near the Great Lakes - ed.] have long-standing differences with their neighbors to the south, who speak what’s known as the Midland dialect. The two groups originated from distinct groups of settlers; the Inland Northerners migrated west from New England, while the Midlanders originated in Pennsylvania via the Appalachian region. Historically, the two settlement streams typically found themselves with sharply diverging political views and voting habits, with the northerners aligning much more closely with agenerally being more liberal ideology.
Labov suggests that it’s these deep-seated political disagreements that create an invisible borderline barring the encroachment of Northern Cities Vowels. When he looked at the relationship between voting patterns by county over the last three Presidential elections and the degree to which speakers in these counties shifted their vowels, he found a tight correlation between the two. And the states that have participated in the vowel shift have also tended to resist implementing the death penalty.
Do vowel-shifters sound more liberal to modern ears? Yes, at least to some extent. Labov had students in Bloomington, Indiana, listen to a vowel-shifting speaker from Detroit and a non-vowel-shifter from Indianapolis. The students rated both speakers as equal in probable intelligence, education and trustworthiness. They also didn’t think they would have different attitudes about abortion (both speakers were female). But they did think the vowel-shifting speaker was more likely to be in favor of gun control and affirmative action.