Republican presidential candidate Donald Trump speaks during a rally March 1, 2016, in Louisville. (John Bazemore/AP)

It was always fairly obvious that much of President Trump’s campaign rhetoric was composed on the fly, often in real-time focus-grouping before enthusiastic audiences. The progressive website ThinkProgress tallied 663 distinct campaign pledges ranging from the familiar — build the wall — to the esoteric: “I will do a better job with the military, I will do a better job with jobs.”

Overlaid with Trump’s famous apathy toward doing his homework, those ad hoc commitments are starting to crumble in the face of political realities. He’s recently abandoned a number of his consistent campaign pledges, such as his insistence that China should be labeled a currency manipulator. The lucky thing for Trump is that his supporters were never rallying to his cause as a function of their strong views on currency manipulation, suggesting that such wavering may not cost Trump politically. New polling from Gallup, though, paints a more complex picture.

The polling firm has asked respondents regularly about their views of Trump’s personal characteristics. On no measure has Trump seen a steeper decline than on the question of whether he’s someone who keeps his campaign promises.

As Gallup notes, that’s probably in part a function of when the polling was conducted. The February poll that set the benchmark came after Trump’s initial executive orders pledging — however effectively — to enact his big-ticket priorities like the ban on immigration and expulsion of those here illegally.

But that decline is weighted heavily to those who already generally disliked Trump. If we compare the decline among groups to exit polling from the 2016 election, there’s a clear link: Those more likely to have voted for Hillary Clinton also saw bigger dips in how much they thought Trump upheld his promises.

(Since Gallup approval polling and exit polls conducted by Edison Media Research use different age groupings than this Gallup poll, we’re comparing 18-to-34-year-olds in the personality trait polling with 18-to-29-year-olds in exit polling. Likewise, we’re comparing the 55-plus age bracket with those 65-plus in exit polls.)

Bear in mind that, by itself, “Trump keeps his promises” is fairly politically neutral: If you hate his promised policy moves, you can still think he will actually uphold them. The decline in the number of liberals who think Trump will keep his promises would probably be relieved to say so.

What I’d like you to pay attention to, though, is closer to the middle of that graph: the independents.

No group that backed Trump in the 2016 election saw a bigger dip in confidence that Trump would enact his promises than independents. As we’ve noted many times before, the group that identifies as “independents” is often made up of people who still generally align with one party or the other, which is one reason they fall in the middle on many polling issues. This is also why men and women are closer to the middle than other groups, since partisan identity is split among the genders more evenly than it is among, say, age groups. But independents have lost confidence in Trump far more than men have.

If we compare the decline in Trump’s overall approval rating with declines in the percent of people who think Trump doesn’t keep his promises, those independents stand out again. While the drop in approval rating among liberals (from very low to slightly lower) and conservatives (from very high to slightly lower) is about the same, the drop among independents since January has been steep.

This matters because Trump’s 2016 coalition was mostly made up of fervent supporters, skeptical Republicans and independents who preferred him over Clinton. (While Trump was generally not trusted, he won easily among the large percentage of Americans who trusted neither him or Clinton.) Trump’s mandate is far smaller than most new presidents and any hope he might have to use his popularity as a cudgel was already weakened by his low approval ratings. If his base of support is reduced to hard-partisan Republicans, his ability to keep his party in line is probably reduced.

Notice that to some extent the drop in the percentage saying Trump keeps his promises is a reversion to the mean: On nearly every other metric he was already in the 40s. Now he’s there on promise-keeping, too.

Americans believed that, all else aside, he was at least leading in the way that he said he would on the campaign trail. They no longer grant him that.