They say x, ask for where they heard about x. They say from y news organization, ask the source for y. If they say z, if z is actually an actual document or otherwise, ask them where in z does y claim x is true.
If z is just another news organization, keep going until they provide (or don't provide) an actual document. If they can't procure an actual document, send it yourself. If z is just another video cIip, ask them for the whole video. Provide them the entire video if they can't.
Do not try to antagonize. Just simply ask the questions as if you were trying to understand their point of view, to learn something we might not have heard.
Most dyed in the wool liberals wouldn't make it that far. I would know, I'm married to one. I tried with the covid and clot shots. Waste of time. Anyone that can be persuaded at worst an independent or moderate. Although at this point in the game i don't see how anyone can be on the fence.