"I'm not going to cut Social Security like every other Republican and I'm not going to cut Medicare or Medicaid," Donald Trump declared in 2015. "Every other Republican's going to cut, and even if they wouldn't, they don't know what to do because they don't know where the money is. I do. I do."

As regular readers may recall, this became a staple of his entire national candidacy: no matter what, Americans could count on him to champion these social-insurance programs. Ahead of the 2016 race, Trump wanted everyone to know that entitlement cuts, as far as he's concerned, are off the table.

Now, however, he's saying something different. Consider the exchange when CNBC's Joe Kernen sat down with the president this morning and broached the subject.

KERNEN: Entitlements ever be on your plate? TRUMP: At some point they will be.... And at the right time, we will take a look at that.

Get the msnbc newsletter. This site is protected by recaptcha

At that point, the president shifted his focus a bit, exaggerating the recent economic growth -- GDP growth, in reality, is both short of his projections and slower than parts of Obama's second term -- seemingly as a way to suggest this would make cuts easier.

Kernen followed up, asking about Medicare and Trump's willingness to "do some of the things that you said you wouldn't do in the past."

The president replied, "We're going to look."

This is obviously the sort of thing that raises any number of questions -- the details matter -- and there are no available answers.

But at its core, there's a basic truth that's unavoidable: ahead of the 2016 cycle, Trump insisted he wouldn't cut any of these social-insurance programs, and ahead of the 2020 cycle, his position is fundamentally different.

And in case that weren't quite enough, there's a larger context that includes Larry Kudlow, the director of the Trump White House's National Economic Council, arguing in the not-too-distant past that the president's team is prepared to look at entitlement "reforms" -- which is a common euphemism for cuts.

As CNBC reported a year and a half ago, Kudlow added that the White House was determined to reduce federal spending, and "part of the Republican plan to curb spending is tackling entitlements."

No matter who wins the Democratic presidential nomination, Trump and his team have made this a key 2020 issue, on which Republicans will be on the unpopular side.

MORE: Today's Maddowblog