VALENCIA, Spain — Press reports often portray Europeans and others overseas as apprehensive when not downright fearful of President Donald Trump. But Trump’s victory has cemented a global alliance of populists, conservatives, and even libertarians who hope a “Trump effect” will sweep away entrenched institutions long controlled by the Left.

Indeed, Trump’s rapid-fire activity since taking office fills them with a mixture of hope and envy. At a summit of populist conservative leaders in Madrid last weekend, prime ministers and opposition leaders called Trump a “brother in arms,” a phrase often repeated, whose lessons they will draw.