It’s an exhausting debate, and one that suffers greatly from a lack of specifics. For all the energy devoted to attacking and defending the integrity of GOP lawmakers, relatively little time has been spent delineating and debating the specific demands Trump’s critics have for Republicans on Capitol Hill. What does it actually mean to “stand up to Trump”? Aside from derailing their entire legislative agenda to punish the president—an unrealistic expectation for any party in power—what exactly do the critics want congressional Republicans to do to hold Trump accountable?

To answer this question, I surveyed a wide range of the president’s detractors—including partisan Democrats, liberal commentators, NeverTrump conservatives, and libertarians. What follows is not a comprehensive catalog of action items for the GOP (much less an endorsement of them). Their responses varied widely, and in some cases contradicted each other. But taken together, they offer to move the debate from the abstract to the concrete, pointing to a gap between what critics would actually like to see done, and what Congress is presently doing.

Protect the Mueller investigation at all costs

Virtually everyone I talked to agreed that the single most important thing congressional Republicans can do right now is to stop the president from shutting down Robert Mueller’s Russia investigation. Trump’s critics contend that any effort by the White House to meddle with the probe would represent a brazen affront to the rule of law.

The prospect of a “Saturday Night Massacre” redux isn’t far-fetched. In recent weeks, Trump has publicly weighed firing Mueller, and press reports have suggested the White House is looking for ways to attack and discredit him. Meanwhile, Trump has all but declared open war on his own attorney general—a bizarre and unprecedented spectacle that many fear portends a Justice Department shakeup aimed at shuttering the Mueller probe.

If Trump is indeed planning an assault on Mueller and his team, Capitol Hill Republicans are uniquely positioned to make the president back down. And yet, so far, the reaction from most GOP lawmakers has been somewhat muted and muffled.

“They should declare that firing the special counsel would cross a red line that would draw the full weight of Congress’s powers to check the executive,” said Austin Evers, executive director of legal watchdog group American Oversight.

What exactly could the “full weight of Congress” look like in this context?

Brian Fallon, a former Hillary Clinton spokesman and senior adviser at Democratic super PAC Priorities USA, suggested a few options for Republicans: Pledge to restore an independent counsel statute if Muller is fired; preemptively declare that removing Mueller would amount to obstruction of justice; and threaten to refuse to confirm a successor to Sessions if Trump fires him.