Speak to the Tribe
If you are correct on the merits, and you are trying to convince someone who disagrees with you, it's best to assume that this disagreement stems from tribal affiliation rather than data. Why? Because that's how humans work, especially with regards to politics. People listen to your message as members of tribes, and if someone doesn't agree with you it's likely in part because their tribe doesn't agree with you.
Basically, you're trying to convince people that you're really part of their tribe, even if it might appear to them that you're not. The best way to do this is to tell stories in their language. Politically speaking, if you're talking to conservatives talk about the continuation of our country's history; if you're talking to liberals talk about fighting for the oppressed; if you're talking to libertarians talk about freedom. The hard part about this is you have to be authentic: you have to tell your story in their language in a way that rings true, and, substantively speaking, is true.
Start with a story, then deliver the data (simply!), then end with a story. To the extent the people in the audience care about the data, you will have given it to them. To the extent the people in the audience are like most people in most audiences, you'll have at least told two stories in their language.