In the case of Trump’s wall, the appropriations record shows that his campaign vision of a massive 30-foot-high, sea-to-sea concrete barrier was pretty much dead on arrival. The 2017 omnibus spending bill — approved by a Republican Congress and signed by Trump soon after his inauguration — insisted that any new barriers follow “previously deployed and operationally effective designs” like steel bollards.

Democrats had a hand in adding this provision, for sure. But the same language became a fixture in 2018 and 2019 spending bills for the Department of Homeland Security. And Trump’s professional advisers soon found they could live with it.

Tests showed that concrete was more vulnerable than steel in the desert heat. As a practical matter, Border Patrol agents preferred to be able to see through the bollards — and not face a blank wall.

The end result was not so much a question of the White House acceding to Democrats as bowing to reality. In the same vein, Trump’s first two fiscal 2018 and 2019 budgets for the Department of Homeland Security — both when Republicans controlled Congress — were relatively restrained in their demands for funding.