I don't know how effective a wall will be but Joe Manchin's the man for being a rebel. I like rebels from whichever political party.
Republicans should think back FDR's days and incorporate in its construction some sort of public works project for young men and women who want to escape Appalachia and the inner cities. This action would either drive a wedge between the Democrats and the poor who they heap empty promise-after-promise upon or perhaps get more Democrats on board.