Donald Trump never fails to surprise. On Wednesday, I thought he would use his trip to Mexico to position himself as a statesman-like, measured President in waiting. Having won a victory by being accorded the image of legitimacy, I believed he would build on this in a speech in Arizona on immigration. This would mean that — rather than repeating the provocative, divisive phrases like “Build the Wall” and portraying immigrants primarily as threats to America — he would pursue a less aggressive line to appeal to undecided voters.

See US Audio Analyses: Why is Trump in Mexico — and Why Did Mexico Invite Him?

I was very wrong.

Instead of appealing beyond his base, Trump doubled down on his confrontation. He not only repeated his fantasy lines about The Wall but added the even more troubling prospect of a Deportation Task Force — armed men sweeping the US for illegal immigrants — “extreme vetting”, and an effective loyalty oath for any immigrant who remains in the US.

So the Trumpian strategy is not to play to the center but to keep up the dog-whistle statements to his base. Can he attract enough Americans with this approach to win in November?

I am now troubled that, against all received political wisdom, he might do just that.

I spoke with BBC Radio WM on Thursday morning, and I had a wide-ranging 20-minute discussion with BBC Radio Three Counties and a Republican voter wondering if he should vote for Trump:

Listen to interview with BBC Radio WM

Listen to discussion on BBC Three Counties

Listen to interview with BBC Radio Foyle

Trump is walking a fine line with this American exceptionalism. He’s getting very close to calling for a loyalty oath, which is something that Americans have generally shied away from.

And when you call for American values, that should be values for all Americans. There are a lot of Hispanic-Americans who came from other countries. Do they really want this type of rhetoric?