Call it the Jerry Maguire moment in blue-state politics. Struggling under the weight of financial promises they’ve made to public-sector unions, governments in places like New Jersey and California need to help Donald Trump help them.

The President is doing just about all he can to enable reform in profligate jurisdictions. His appointment of Neil Gorsuch to the Supreme Court—the most consequential of many great Trump hires across the government—led to Wednesday’s Janusdecision ending the blue-state habit of forcing public...