Hospitals sued the Trump administration yesterday over its requirement that they disclose their negotiated rates, the latest of the industry's moves to protect itself from policy changes that could hurt its revenues.

Why it matters: Hospitals account for the largest portion of U.S. health costs — which patients are finding increasingly unaffordable.

The big picture: Hospitals are going to war against Trump's price transparency push while simultaneously trying to kill Democrats' effort to expand government-run health coverage.

The industry is one of the main forces behind the Partnership for America's Health Care Future, the group that's gone on offense against "Medicare for All" and every other proposal that would extend the government's hand in the health system, as Politico recently reported.

It's also emerging victorious from blue states' health reforms so far, which all started as proposals much more threatening to hospitals than the watered-down versions that eventually replaced them.

Between the lines: The industry has a lot to lose; even non-for-profit systems, as my colleague Bob Herman put it, "swimming in cash."

The Trump administration's transparency measure could lead to either more pricing competition or further regulation, if it exposes egregious pricing practices.

And Democrats' proposals often feature government plans that pay much lower rates than private insurance does.

Hospitals argue that the transparency measure could end up raising prices if providers with lower negotiated rates see what their competitors are getting. They also warn that Democrats' plans could put hospitals and doctors out of business and threaten patients' access to care.

The bottom line: Politicians are reacting to patients' complaints about their health care costs, but the industry has historically been excellent at getting its way.

Go deeper: Hospitals winning big state battles