no, you're wrongWhy mention "Mexico" even if Trump did lie about them paying for it.
This is Trump's issue that he needs to resolve himself so why allow him to have an escape route and add the Mexico variable?
If they did mention Mexico alll that does is give Trump room to shift the focus off him and onto them in that moment. I could see him saying "Mexico is un-trust worthly and corrupt - they lied about funding the wall because they want to send their people here"
Mexico is a mute point in this argument. However if he decides to mention Mexico then you attack him on it.
it doesnt get much clearer than 'im gonna make mexico pay for the wall'. it's such an easy opportunity to make him look like a weak businessman or a liar when he needs my tax dollars
and i already stated my evidence for this. everyone republican who gets asked this point blank has to laugh it off or deflect because it's a lie