One thing that hasn’t really changed since President Trump was inaugurated is that most Americans don’t think he’s doing a very good job. Gallup had Trump’s approval rating at 45 percent during the first week of his presidency; it’s now at 40 percent. During the intervening 28 months, his rating has never been higher than 46 percent or lower than 35 percent. He’s just bouncing up and down in that narrow range, essentially as popular now as he was then.

What have changed are the rationales offered to explain why Americans do or don’t think Trump is doing a good job.

On Wednesday, CNN published the results of a new poll it conducted with its polling partner SSRS. In addition to asking respondents if they approved of the job Trump was doing (43 percent did), they also asked people to explain why they felt that way. The most common response? His handling of the economy.

This isn’t really a surprise, in part because Trump himself has focused on the economy as a rationale for supporting him. But it is interesting to compare those responses to the ones The Post and our partners at ABC News heard when we asked a similar question in July 2017. (At the time, we measured his approval at 36 percent.)

Our question didn’t allow for multiple responses, meaning that the response categories are generally fewer and smaller than what CNN and SSRS heard. We also had to occasionally group responses in order to compare the two data sets, which could mean that some responses in the CNN poll are double-counted. Nonetheless, some fascinating patterns emerge when considering the changes.

Notice, for example, how significantly the economy has grown as a rationale for supporting Trump. This makes sense, given that Trump’s ability to claim ownership over the economy in July 2017 was a bit more modest than it is now. Regardless, the shift is noteworthy — large enough to force us to redesign our graphic to make the changes more clear.

Interestingly, the number of people who say he is keeping his promises has not changed much — a function, perhaps, of Trump’s “promises” being considered mostly in the abstract.

A few things cited in 2017 have dropped off the radar entirely, such as the Republican health-care law and Trump’s Supreme Court nominations. A few other categories have grown a bit, such as the one for those who like Trump because he’s “making America great again.” Trump’s handling of foreign policy, on the other hand, has dwindled as a rationale for supporting him. (The growth in “strong leadership” deserves an asterisk, given that we aggregated a number of categories from the CNN poll in order to compare the two.)

It’s not only Trump supporters who have changed their reasoning. We can also compare the reasons offered in 2017 and 2019 among those who don’t think Trump’s doing a good job. (That figure was 58 percent in our 2017 poll and is at 53 percent in CNN’s.)

As with “strong leadership” in the prior chart, we combined a number of categories to match “inappropriate behavior” from the 2017 poll.

That broad “behavior” category was not what CNN identified as the most common response (since it is a combination of multiple responses). Instead, the 13 percent who say Trump is dishonest or lacks integrity expressed the most common response in CNN’s poll — about where we had him two years ago.

The two biggest growth categories over that period have been significant ones. In CNN’s poll, Trump detractors were much more likely to point to their perceptions that Trump is racist or bigoted than respondents were in 2017. They were also much more likely to point to issues related to corruption and ethics than when we asked a similar question.

There may be a reason for that latter increase in the perceptions that Trump is corrupt. Notice that one of the reasons offered in 2017 was concerns about Russia and the Russia probe. That vanished in CNN’s responses — but the increase in concerns about corruption may reflect the volume of special counsel Robert S. Mueller III’s report in which he details ways in which Trump appeared to want to derail the investigation.

Another area that decreased since 2017 was concern about immigration, mostly manifested in CNN’s survey as frustration over Trump’s family separation policy. In fact, most of the responses from those who view Trump unfavorably had little to do with his policy choices and were, instead, focused on him as an individual. That’s probably not a good sign for Trump if he hopes to woo skeptical voters in 2020.

What these polls suggest, though, is that no amount of wooing was likely to be effective anyway. Trump has never really come close to majority approval. Maybe people have changed their rationales for why they do or don’t like him, but not many people have actually changed their minds about him overall.