As a coda to President Trump’s failed government shutdown strategy, it is difficult to find something more brutal than this:

After a 35-day partial shutdown, in which Trump and the GOP held the government’s funding hostage in exchange for a border wall, people prefer Democrats on the issue of border security.

A new Quinnipiac University poll finds Americans trust Democrats more than Trump on border security, 50 percent to 41 percent. That is up from a 49-to-44 Democratic advantage two weeks ago. Both findings are rare since the issue has almost always favored the GOP.

As recently as November, a Washington Post-ABC News poll found people favored Republicans to Democrats on the issue of border security by nearly the opposite margin, 49 to 39. A few months earlier, in July, a Post-Schar School poll provided more options but found the same margin: Americans favored the GOP on the topic by 10 points, 37 to 27.

Fox News polling has also tested this question over time and has always found a significant GOP edge. In September of last year, it was 11 points. In June, it was 14 points. And in 2010, it was as high as 20 points, 48 to 28.

These polls all tested Republicans against Democrats rather than Trump against Democrats, but if anything, Trump’s margins on this question have been bigger than his party’s.

Pollsters generally test the broader issue of immigration more than “border security,” and the immigration question usually provides a more even split. But when the question turns to enforcement, Republicans tend to be favored because of their more hard-line stances.

Trump has taken that to a whole new level, proposing a Muslim ban, enacting a travel ban, separating families at the border and now framing the border situation in terms of a national emergency that requires physical barriers. Yet the new poll shows independents favor Democrats to Trump on this issue 50 to 37.

But while talking tough, Trump has gotten behind proposals that are not popular with the American people. Ending protections for the children of those in the country illegally was one, and the border wall is another (only about 4 in 10 Americans favor one). Trump’s decision to combine that demand with an unpopular shutdown appears to have hurt him on one of his signature issues.

This could certainly be a blip in the long-term trend — the last time the GOP’s numbers on border security ebbed was in 2006, amid a failed comprehensive immigration reform push by George W. Bush — but Trump seems to have badly undermined his own brand on one of the issues he cares most about. Either because people see him as supporting things they don’t like or simply see him as ineffectual, the practical effect is that they do not trust him on this issue of such importance to him.

Continuing to push for a border wall and possibly losing (again) looks like an increasingly bad idea.