The others melted into the wings. And though Sanders engaged Clinton at times sharply on the economy, Wall Street, and the use of military force, Clinton responded forcefully (including by going on offense on gun control, where she outflanks him to the left). More importantly, she deftly navigated a course that closed her ideological distance from the populist insurgent where possible while keeping one eye fixed on the general-election horizon. That is, where she couldn’t parry, Clinton would simply redirect, dropping a reminder that Democrats’ real fight is with the opposing party.

Clinton came into the debate with two pressing vulnerabilities. The first hinged on the steadiness of her conviction. As President Obama’s first Secretary of State, for example, she spent years advocating for the Trans Pacific Partnership, the massive trade deal that she denounced last week. For some, that flip-flop emblematized an opportunistic approach to key policy debates. Citing it, CNN moderator Anderson Cooper asked Clinton pointedly if she’d say anything to get elected — and then asked her to state whether she’s a progressive or a moderate. “I’m a progressive,” Clinton replied, “but I’m a progressive who likes to get things done, and I know how to find common ground, and I know how to stand my ground, and I’ve proved that in every position that I’ve had.” The moment demonstrated Clinton’s ability, on this night anyway, to answer an “A or B” question by saying, “Yes,” without appearing to be wiggling away in the process.

Clinton faced a second crucible over lingering questions about her use of a private email server as Secretary of State. The scandal has dogged Clinton’s entire campaign, and while her relatively new glasnost approach has given her some practice addressing it, a wrong note could have soured her otherwise command turn. But when it finally came up, roughly halfway through the proceedings, Clinton got a gift. After repeating her mea culpa, she argued that the Congressional investigation that uncovered it looks increasingly like a partisan mission and she’d rather get back to discussing policy. Then, unexpectedly, Sanders jumped in to defend her. “Enough of the emails!” he said to applause from the crowd gathered at the Wynn Las Vegas hotel-casino. “Let’s talk about the real issues facing America.”

Clinton, beaming, thanked him and shook his hand. A discussion of the issues placed her on much firmer ground. And there again, Sanders arguably did her a favor by staking out positions so far to the left that Clinton had plenty of room to maneuver. At the very beginning of the debate, Sanders declined to call himself a capitalist. “Do I consider myself part of the casino capitalist process by which so few have so much and so many have so little, by which Wall Street’s greed and recklessness wrecked this economy?” he said, reformulating the question. “No I don’t. I believe in a society where all people do well, not just a handful of billionaires.”

That teed up an opportunity for Clinton to sound measured: “When I think about capitalism, I think about all the small businesses that were started because we have the opportunity and the freedom in our country for people to do that and to make a good living for themselves and their families,” she said. “And I don’t think we should confuse what we have to do every so often in America, which is save capitalism from itself.”

Clinton declined to endorse a call from former Maryland Gov. Martin O’Malley to reinstate the Glass-Steagall Act’s separation of commercial and investment banking. And while Sanders inveighed against the influence of big-money Super PACs, Clinton’s bid is benefiting from their support and she stayed quiet on the issue. Those are evidently indulgences she can afford despite a restive liberal base.