Donald Trump got elected the 45th president of the United States thanks to one simple word: Change.

Voters desperately wanted something different than politics as usual and the same old politicians. Trump represented that something different. Hillary Clinton didn't.

The exit polls from 2016 tell that story powerfully. Nearly 4 in 10 exit poll respondents said that a candidate who can bring about real change was the most important quality in making up their minds. Trump won that group 82 percent to 14 percent over Clinton. Game, set, match.

"Change" is, of course, a very nebulous idea.  It means very different things to different people. And one person's idea of the right change that needs to come to Washington might not necessarily — or ever — be another person's idea of it.

Now that Trump has been president for a month — and people have gotten the chance to see what he meant by "change" (travel ban, building the wall, etc.) — many of them don't seem to like what they are getting.

Compare Quinnipiac University polling from right after the election to now. In the immediate wake of the election in November, 46 percent of voters said that Trump represented the "right" kind of change, while 33 percent said he represented the "wrong" kind of change. In a Q poll this week, 38 percent said Trump represented the right kind of change, while 45 percent said he was bringing the wrong kind.

And it's not just Quinnipiac with results like that. Take McClatchy-Marist University polling. In December, 44 percent said Trump represented change for the better, while 34 percent said he represented change for the worse. Now 44 percent say he is making changes for the worse, and 40 percent say his changes are for the better.

Those numbers should be concerning to Trumpworld. The central question of his presidency — and particularly his chances of being reelected — is whether voters believe he delivered on the change they voted for. That was always going to be a tough challenge because — as I noted above — change means different things to different people. And Trump was very, very vague about what exact changes he would institute, making it even tougher to figure out how to measure success or failure.

What is clear: Trump needs to be on the "right" side of change for his own political fortunes. And right now, he's not.