Try as you might, no one is lumping Reagan and Buchanan together other than agreement on some issues, fair trade being one of them.
It's easy to call people names like demogogue, we're all guilty of it. But my hunch is any politician who favors tough enforcement both at the border and in the interior is a demogogue to you. I got news, that label would fit 80% of the population as well who've had enough of open borders.
I suppose that it is remotely possible that the smallest group could finesse a program thru Congress, but it is most likely that a compromise bill with broad support is the one.
You also ignore the distinct possibilty that there is a Congressional Charade in process. This charade allows all house republicans to appear tough and in the end, only a few republicans in the senate and those republicans on the conference committe catch any blame.