It's not a prejudice to say that politicians use wedge issues like gun control and immigration to manipulate voters into casting votes that are contrary to their own interests. It's also not a prejudice to say that a lot of voters are manipulated into doing that by politicians using wedge issues in that way. Those happen to be facts and it's why so many elections are essentially won or lost on those kinds of wedge issues. And that's what Obama was saying. But some people are allowing their own prejudices to cause them to read things into what Obama was trying to say that aren't there.

Obama was saying that disillusionment with the government is causing a lot of voters, particularly those who live in areas that are hard hit economically, to vote against their own economic interests because of politicians who are manipulating them into doing so using wedge issues. And he was telling people who would be campaigning for him some talking points they could use when they encountered such people.