On Wednesday night, Bernie Sanders appeared on MSNBC and noted a persistent political challenge. “There’s a huge gap right now between Congress and the American people. What presidential leadership is about closing that gap,” he said . Asked if he believed President Obama had closed that gap, Sanders added, “No, I don’t. I mean, I think he has made the effort.”

For Democrats, this perspective has it largely backwards – if there’s a “huge gap right now between Congress and the American people,” Dems argue, it’s because Congress is run by radicalized Republicans who won’t compromise and who remain indifferent to pressing national needs. Suggesting the White House is somehow to blame is central to the GOP’s pitch.

Which, of course, makes it precisely the sort of rhetoric that Hillary Clinton is eager to use against her rival. Indeed, it led to an exchange in last night’s debate in Milwaukee that helped capture much of what the Democratic primary is all about. As MSNBC’s Alex Seitz-Wald reported

“The kind of criticism that we’ve heard from Senator Sanders about our president I expect from Republicans,” Clinton said. Sanders, clearly agitated, called that a “low blow” and shot back, “one of us ran against Barack Obama. I was not that candidate.” “Last I heard, a United States senator had the right to disagree with the president, including a president who has done such an extraordinary job,” he said, his voice growing louder.

Clinton had a detailed response at the ready. “You know, senator, what I am concerned about, is not disagreement on issues, saying that this is what I would rather do, I don’t agree with the president on that, calling the president ‘weak,’ calling him a ‘disappointment,’ calling several times that he should have a primary opponent when he ran for re-election in 2012, you know, I think that goes further than saying we have our disagreements.”

For the former Secretary of State, President Obama is both sword and shield. When pressed on some of the more controversial aspects of her record, Clinton notes the similarities between her and the president – effectively daring Sanders to condemn Obama directly. When given the opportunity to go on the offensive, Clinton uses Obama to question the independent senator’s loyalty and commitment to a Democratic agenda.

It’s a message that played well among Dems in Milwaukee, but just as importantly, it’s likely to land on fertile soil in South Carolina, where Democrats give the president a 93% approval rating.

Just as importantly, I got the sense Clinton, after months of campaigning, finally figured out what she wanted to say about the persistent opponent who’s turned out to be far stronger than expected. It came, oddly enough, in Clinton’s closing statement in the final couple of minutes of the event.

“You know, we agree that we’ve got to get unaccountable money out of politics. We agree that Wall Street should never be allowed to wreck Main Street again. But here’s the point I want to make tonight. I am not a single-issue candidate, and I do not believe we live in a single-issue country. I think that a lot of what we have to overcome to break down the barriers that are holding people back, whether it’s poison in the water of the children of Flint, or whether it’s the poor miners who are being left out and left behind in coal country, or whether it is any other American today who feels somehow put down and oppressed by racism, by sexism, by discrimination against the LGBT community, against the kind of efforts that need to be made to root out all of these barriers, that’s what I want to take on. “And here in Wisconsin, I want to reiterate: We’ve got to stand up for unions and working people who have done it before, the American middle class, and who are being attacked by ideologues, by demagogues. Yes, does Wall Street and big financial interests, along with drug companies, insurance companies, big oil, all of it, have too much influence? You’re right. “But if we were to stop that tomorrow, we would still have the indifference, the negligence that we saw in Flint. We would still have racism holding people back. We would still have sexism preventing women from getting equal pay. We would still have LGBT people who get married on Saturday and get fired on Monday. And we would still have governors like Scott Walker and others trying to rip out the heart of the middle class by making it impossible to organize and stand up for better wages and working conditions. So I’m going to keep talking about tearing down all the barriers that stand in the way of Americans fulfilling their potential, because I don’t think our country can live up to its potential unless we give a chance to every single American to live up to theirs.”

There’s no denying the fact that Sanders is a disciplined candidate with a powerful message: big banks and the very wealthy have rigged the economy in their favor, squeezing the middle class and creating unsustainable economic inequality. But if you listen to Sanders in a forum such as a debate, it’s obvious that he routinely works these concerns into as many answers as humanly possible. Whether you consider his focus “specific” or “narrow” depends largely on whether or not you’re inclined to support him.

But Clinton seems to believe she can start using this specificity against Sanders, characterizing him as a “single-issue candidate.” Clinton hopes Democrats start to see Sanders, who has admitted more than once that his campaign is doing far better than even he expected, as a protest candidate highlighting the issue he cares most about – which isn’t necessarily bad, but which doesn’t necessarily make him presidential material, either.

The White House is about breadth and complexity, the argument goes, and even if you agree with Sanders, it’s hard to deny his principal focus on the one issue that drives and motivates him.

As Slate’s Jamelle Bouie put it , “She paints the Vermont senator as too blinded by his focus to see or understand the unique problems faced by different minority and underprivileged groups, as evidenced by his clear discomfort with topics outside of income inequality…. She zeroes in on Sanders’ great strength – his incredible consistency – and makes it a liability.”