Hillary Clinton's campaign has spent the past few days indulging its worst instincts. It blundered into a dumb attack on Bernie Sanders, but rather than back down it raised the stakes. The result has been a reminder, to liberals, of what they like about Sanders and mistrust about Clinton. But it's also been a missed opportunity for Clinton to make the case to Democratic primary voters that she should have been making all along.

The subject was Sanders's support for a single-payer health care system. The policy puts Clinton in a bind: It's popular with liberals but dangerous in a general election. Sanders's support for it is, to Clinton, everything wrong with his campaign in miniature — it's an idea that sounds good on the stump but really reveals a preference for ideological symbolism over the hard work of policy change.

In 1994, Clinton spearheaded a doomed overhaul of the health care system. I've interviewed dozens of people who worked with her on that effort, and who have worked with her since that effort, and the lessons her team took away are clear and deeply held. When it comes to health reform, do not screw with what people already have.

The Clinton plan wasn't single-payer, but it was a lot closer than what we have now. Her plan would have upended the insurance of virtually everyone in America. And it was eviscerated because of it. The fact that, on net, there would have been many more winners than losers didn't matter. That much disruption is impossible to pass through the American political system. It set the cause of universal health care back a generation.

Clinton's view is that anyone who actually cares about insuring the uninsured needs to grapple with the power of the status quo — and Sanders hasn't come close. He hasn't even released a real plan, which, quite fairly, drives Clinton nuts. "The devil's in the details when it comes to health care," she told Rachel Maddow.

Obamacare, meanwhile, rests on shaky ground. Barely 60 percent of states have even accepted the Medicaid expansion. And one of the prime arguments against Obamacare is that, modest as it was, it still canceled some insurance plans. For Sanders to crash into this debate with a vague proposal to cancel many, many, many more is to imperil the fragile gains that have already been made.

But Clinton doesn't trust Democratic primary voters to listen to that argument. Pragmatism might win in policymaking, she believes, but inspirational fantasies win primaries. So her campaign has, instead, tried out a series of attacks on Sanders meant to confuse primary voters about where the two candidates actually stand.

Clinton's three attacks on Sanders

One version of the attack accuses Sanders of raising taxes on middle-class Americans. "There is no way that can be paid for without raising taxes on the middle class," Clinton said in Iowa. "The arithmetic just doesn't add up."

Here, Clinton is neglecting to mention that those taxes would replace the insurance premiums people are already paying, and would likely be lower than the insurance premiums people are already paying. If single-payer is cheaper than the current health care system — and most experts believe it would be — then the net result would be less spending.

Clinton knows all this perfectly well. There is a special irony to her playing this particular game. A major blow to her 1994 health care plan came when the Congressional Budget Office decided to count the premiums people would pay as new taxes — a decision the Clinton administration bitterly opposed, and that former officials complain about to this day.

The next version of Clinton's attack criticizes Sanders for a past single-payer plan he sponsored that would rely partly on state contributions for funding.

"[Sanders] wants to roll Medicare, Medicaid, the Children's Health Insurance Program, the Affordable Care Act program, and private health insurance into a national system and turn it over to the states to administer," Clinton said, warning that could be "a big problem" if Republican governors refuse to pay their share.

Here, again, Clinton knows better. Medicaid, the Children's Health Insurance Program — which she helped create — and Obamacare are already administered by the states and already rely on state funding. Sanders's plan would reduce the share of contributions states are responsible for and provide a federal fallback that doesn't currently exist if states refuse to participate in those programs.

Meanwhile, the private health insurance system leaves out millions of people who aren't covered under Obamacare — Sanders's plan would almost certainly lead to more Americans with health insurance than the status quo.

A third version of the attack was handed to Chelsea Clinton to launch. "Senator Sanders wants to dismantle Obamacare, dismantle the CHIP program, dismantle Medicare, and dismantle private insurance," she said. "I worry if we give Republicans Democratic permission to do that, we'll go back to an era — before we had the Affordable Care Act — that would strip millions and millions and millions of people off their health insurance."

Here, the disingenuousness becomes farce. The idea that folding a patchwork of smaller programs into a single universal program represents "dismantling" those programs — much less giving Republicans permission to dismantle those programs — flies in the face of basically every Democratic attempt to expand social insurance ever. The 1994 Clinton health care plan, to name just one example, "dismantled" virtually every existing insurance arrangement in the country in order to create a single, unified structure that could cover more people.

On Thursday, Clinton appeared on The Rachel Maddow Show and was given another opportunity to either back off these arguments or make a better case against Sanders's plan. But again, she chose not to.

"Do you disagree with single-payer as a goal?" Maddow asked.

"No. I agree with universal health care," Clinton replied, subtly changing the subject.

Maddow tried again. "No matter how we get there?" she asked.

"No matter how you get there," Clinton replied.

This statement almost certainly isn't true. It's easy to imagine awful ways to achieve universal health care — financed through a tax on the poorest Americans, for instance, or built atop regulations that stifle medical innovation. A thoughtful, serious argument about why single-payer isn't the best path forward would have won Clinton more fans than this kind of obvious pandering.

Clinton went on to reprise her argument that the real problem with Sanders's plan is that it would try to get states to administer the health care programs, though, again, she never mentions the federal fallback in the scenario where states refuse to build out their plans.

The result is that Clinton argued in one breath against Sanderscare, which works like a supercharged version of Obamacare, and then in the next breath called Obamacare "one of the signature accomplishments, not just of this president but of the Democratic Party," and said she was running to defend it.

All this, though, is Clinton's attempt to obscure the big picture: Sanders supports a single-payer health care system, and she doesn't. The technical arguments she's making about past legislation he's proposed could all be addressed if the bills moved forward. That's not the real disagreement between Clinton and Sanders. The real disagreement is he thinks we should move forward on single-payer, and she doesn't.

The Clinton that voters don't get to see

Behind these attacks lurks a deeper problem that bedevils the Clinton campaign: They don't trust voters to like Clinton the candidate for who she is.

Clinton's reputation, among people who've worked with her, is impressive. Even Republican staffers will admit they've never briefed anyone better informed. Stories abound of unsuspecting deputy assistant secretaries charged with running a meeting on some obscure sub-issue only to be peppered by detailed, knowledgeable questions from Clinton herself. During her time in the Senate she won over legions of ex-haters with her work ethic, her seriousness, and her pragmatism. Even people who didn't agree with her appreciated her no-bullshit attitude toward getting things done.

Another way of saying that, though, is Clinton wins over even people who disagree with her by treating their ideas with respect — she takes the time to understand their arguments, she's honest about her counterarguments, and she is relentless in her efforts to find shared ground on which to make progress.

The problem is Clinton doesn't campaign the way she governs. She often seems scared to tell voters what she really thinks for fear they'll disagree. Her knowledge of the painful trade-offs of governing can curdle into a paralyzing recognition of all the ways she could be attacked for taking a clear position.

And that's a shame. Clinton's best political quality is that she truly understands both the issues and the political institutions that mediate them. Her true, unfiltered opinions on these topics are earned by long experience and almost inhuman amounts of hard work.

In the debates, she's frequently dominated the stage simply by knowing more than anyone else on it — which is one reason it was so counterproductive for the Clinton campaign to limit the number of Democratic debates to six and ensure they would only be showed at ridiculously inconvenient times. But that, too, stemmed from their mistrust of a press and an electorate that they worry won't respond to Clinton's best qualities.

The argument for Clinton is that she's the Democrat most likely to make progress on progressive priorities because she's the Democrat who best understands both the issues and how unbelievably difficult it actually is to get anything done in a divided political system. Sanders can talk all he wants about political revolutions, but no one seriously doubts that the next Democratic president will face a Republican House, a 5-4 Republican majority on the Supreme Court, and a country that mistrusts government action.

In that world — the world we actually live in — there's a strong case to be made for a pragmatic approach that respects the sensitivities of the electorate and the power of the status quo. Liberals might disagree with Clinton's true position on single-payer, but I think they would respect it. Instead, in her effort to avoid that disagreement, she's blundered into a position that no one agrees with and no one respects. Worse, it's a position that makes people think Clinton doesn't respect them.