On the campaign trail, the call and response was a feature of every rally: "Who's going to pay for the wall?"

"Mexico!"

President Trump is standing by that, but his tweet Sunday morning shows that it has become a bit more complicated now that he's in office...

The context: Trump wants funds to start the wall included in a spending bill that must pass this week to avoid a government shutdown. The obvious question from his critics is, "didn't you say Mexico was paying?"