Legislators step up when enough of their voting constituencies make it clear that they value something as a non-negotiable (assuming votes still matter). Which

Legislators step up when enough of their voting constituencies make it clear that they value something as a non-negotiable (assuming votes still matter). Which means those who care about this are back to not only contacting legislators but also persuading a lot fellow voters that separation of powers is crucial and worth prioritizing over familiar well-handled and loved heuristics.