Jeff Flake wants to know when Republicans abandoned their beliefs. In an excerpt from his new book, published Monday in Politico Magazine, the junior senator from Arizona mourns the status of the Republican Party in the age of Donald Trump, contrasting the “principled constitutional conservatives” of the past with a GOP that has “rationalized” away its principles, brought dysfunction to the “highest levels” of the government, and “maintained an unnerving silence” as instability ensued in the executive branch.

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Flake’s lament is genuinely remarkable. It is highly unusual for politicians to publicly criticize party leaders, to say nothing of co-partisans in the White House. And it’s virtually unheard for that criticism to take the cutting tone that Flake has levied against the president and the Republican Party writ large. Indeed, while Trump is the main target of his rhetoric, he also makes an oblique indictment of congressional leaders, presumably figures like House Speaker Paul Ryan and Senate Majority Leader Mitch McConnell. And there are points where it seems as if Flake is outright questioning the pursuit of conservative priorities, given the larger threats to American democracy. “If by 2017 the conservative bargain was to go along for the very bumpy ride because with congressional hegemony and the White House we had the numbers to achieve some long-held policy goals—even as we put at risk our institutions and our values—then it was a very real question whether any such policy victories wouldn’t be Pyrrhic ones,” he writes.

Flake isn’t the only Republican to articulate these concerns. Nebraska Sen. Ben Sasse has also voiced his uneasiness about the present state of affairs in the Republican Party. In an essay on Sasse, my colleague Ben Mathis-Lilley notes how the senator’s public profile is increasingly defined by this public grappling with both the president and the GOP, how he “sets himself apart by frequently challenging his party on their behalf.”

For liberal critics of President Trump and the Republican Party, this dissent is welcome. It’s also frustrating. Flake’s rhetoric (and Sasse’s) implies a set of actions—an open break with the president and GOP leadership, and a willingness to use their leverage as senators to expose the Trump administration to needed sunlight. But thus far, this rhetoric is just that—rhetoric, untethered to any action.

In fairness to both senators, they aren’t the only ones to find themselves in this position, where their rhetoric outpaces what they’re willing to do. Last year, as Trump barreled through the Republican presidential primaries, Mitt Romney gave an impassioned speech against his candidacy, blasting the demagogic reality-television star as a threat to the republic itself:

Mr. Trump is directing our anger for less than noble purposes. He creates scapegoats of Muslims and Mexican immigrants. He calls for the use of torture. He calls for killing the innocent children and family members of terrorists. He cheers assaults on protesters. He applauds the prospect of twisting the Constitution to limit First Amendment freedom of the press.

This is the very brand of anger that has led other nations into the abyss.

Like Flake’s essay, Romney’s speech implied a clear course of action: Should Trump win the nomination, he would endorse the Democrat in the race, Hillary Clinton, and help build a united front against a figure he denounced as dangerous to the nation’s well-being. But Romney wouldn’t take that step. When “President Trump” seemed unlikely, Romney was ready to stand against his bid. When, suddenly, “President Trump” seemed very possible, Romney was absent, unwilling to follow his rhetoric to its conclusion.

Romney wasn’t alone. Other Republicans who denounced Trump in harsh terms before he won the nomination—like his rival John Kasich of Ohio or onetime presidential candidate Jon Huntsman—were silent in the wake of his victory, dismayed at Trump’s success but reluctant to take the one step that might block his path to the White House.

There is an obvious response here, one that makes sense: Public opposition is a major step. We can’t expect Republicans to behave like Democrats. In Romney’s case, this means he wasn’t obligated to support Clinton, even if his rhetoric pointed in that direction. Likewise, it’s unreasonable to think that Flake or Sasse would vote against a conservative Supreme Court nominee, or tax cuts, or Obamacare repeal, just because of their views on party leadership. They may oppose Trump and have harsh words for figures like McConnell, but they’re still Republicans and conservatives.

This rejoinder would fit if Flake, Sasse, and others were more measured in their rhetoric. But they aren’t. To expect them to act as actual obstacles to Trump is to hold them to their own standards. And it ignores the extent to which there are actions they can take that fulfill their words without jeopardizing their conservative beliefs. Flake, for example, sits on the Senate Judiciary Committee. He has direct authority to hold the president accountable through requesting testimony, documents, and other materials. If he is concerned with the president’s entanglements with Russia, he can condition actions on judicial nominees with greater transparency from the White House. It is within his power and ability to shine a spotlight on the administration.

That he hasn’t taken this step, or any other, might suggest a certain amount of cynicism in this criticism. Come next year, Flake will be running for re-election in a state that is trending away from Republicans, and away from Trump in particular. Perhaps he is trying to distance himself from the president without putting too much space between himself and his party. Perhaps he is trying to have his cake—a reputation for principled conservatism—and eat it too.

If so, it’s understandable. Making a decisive break with one’s party doesn’t just threaten one’s political future; it jeopardizes actual relationships, too, and can end in the kind of isolation that makes it difficult to accomplish priorities and help constituents. It makes sense that Flake would not want to bear that cost, even if he has real misgivings about the course of the GOP.

But if that is true, then it should change our understanding of his rhetoric. Flake’s lament, like Romney’s election-year rebuke, should be understood less as independence and more as a sharp example of the rigid partisanship we’ve come to expect from politics. It is a partisanship so unyielding that, even when politicians oppose their leaders as threats to democracy, they don’t feel they can do anything about it.