Such an offer would reset the terms of the budget fight so it’s about something more than money and the wall. Mr. Trump would be offering Democrats something they claim to want, and they’d look small and cynical if they failed to consider it. Democrats would have to explain to Dreamers and their families why they prefer to deny Mr. Trump a half victory rather than improve the lives of hundreds of thousands of anxious young adults.

Mr. Trump would take some heat from the restrictionist right that would call any legalization “amnesty.” But these are the same voices denouncing him for not getting funding for the wall. They can’t have it both ways. House Democrats aren’t going to give Mr. Trump money for the wall unless they can tell their voters they won something too.