If there's some reason you can't uninvite them, then the best solution is probably to establish a blanket ban on politics discussion for the entire trip. This can sometimes work (and means you can cut off any attempt to start with a quick "remember, no politics!") and might be a welcome break for your other friends too. If they seem like the sort of people to "forget" that when drunk, or refuse to accept the agreement, then frankly that's a valid reason to univite them on its own.

But really, reconsider whether they need to come along. At some point you have to accept that some people aren't the kind of people you want to holiday in France with, and it doesn't sound like literally anyone else is looking forward to spending time with them. It sounds like you're early enough in the planning that now's the time to do it.