That Bernie Sanders-Hillary Clinton Slugfest? It Didn’t Happen, and It’s Not Going To.

Twice now the candidates have had a chance to go for the jugular, and both times they’ve steered far clear.

The tension between Hillary Clinton and Bernie Sanders over the latter campaign’s data theft was supposed to explode during Saturday night's Democratic. That didn’t happen.

Here's what did: Sanders admitted his campaign had done “the wrong thing” by looking at the Clinton camp’s data, though he added his staff had a previous opportunity to look at those data and had done “the right thing.” He said he had fired the person responsible. He accused the Democratic National Committee of treating his campaign unfairly in the aftermath of the data theft revelations. Then came the big moment: He apologized to Clinton. Clinton not only accepted, she dismissed it as an important issue in the campaign—an echo of Sanders’ first-debate line that the American people “don’t give a damn” about Clinton’s emails.

And that was it. The conversation moved on to issues of national security and gun regulation, the issue was gone for the evening, and the bitter, personal struggle between Clinton and Sanders that debate watchers were waiting for never happened.

And guess what? It’s probably never going to.

If a face-to-face throwdown full of personal attacks was ever in the cards, they would be on the table already. Both candidates have now had a chance to go for a crushing personal attack—and both not only passed, they came to their rival’s aid: Sanders waived away Clinton’s private email server, Clinton dismissed the Sanders campaign’s data peek as a nonissue. (Yes, their campaigns did some sniping, such as this agressive tweet from a Sanders advisor. But both times when given a high-profile stage for a face-to-face attack, the two played nice.)

What accounts for the lack of personal animus?

In short: Sanders can’t win with personal attacks, and Clinton can win without them.

For Sanders, it may be that he just can’t bring himself to use the tactics that resemble those of a standard campaign. Or it may be that he knows that many of his supporters are with him specifically because he doesn’t resemble a standard campaign. He promised not to go negative, he swore off super PACs, and he has built his campaign around support for a specific set of policy positions. If he strays too far from that, he risks losing the luster of idealism that pulls supporters to him to begin with. (It's not for nothing that, immediately after apologizing to Clinton, Sanders offered a second apology, this time to his supporters, telling them it was not the kind of campaign tactic he supported.)

Similarly, Clinton has little to gain from attempting to bury Sanders by undercutting his character. She’s still the clear favorite to win the party's nomination, and after a summer in which Sanders put a scare into her camp with some solid poll numbers, she again appears well on her way to a primary win. After that, she’ll need support from the liberal base that’s backing Sanders when she gets to the general election. That doesn’t just mean votes, it also means convincing people to volunteer, organize, and donate with the same vigor that they're now doing for Sanders. And when Clinton asks Sanders’s followers for their zealous support, she’ll have a much better chance of getting it if she defeats their candidate without demonizing him.

Instead of personal attacks, they’re both taking a safer route, one that protects Sanders’ movement and Clinton’s general election prospects. And that means sparring (sometimes politely, sometimes less so) over policy.

That realm, on Saturday night, is where the gloves came off a bit. Sanders hit Clinton repeatedly on foreign policy, knocking her vote for the Iraq War when she was in the Senate and saying she was too supportive of the types of foreign interventions that, Sanders said, have landed the U.S. in quagmires.

For her part, Clinton took on Sanders over his plans for health care (single-payer universal coverage) and education (free tuition), saying she would not raise middle-class taxes while his programs, by virtue of their huge price tags, would be dependent on doing so. Sanders countered that his programs were a good deal for the middle class even if it involved a tax increase, and the two were on the verge of a discussion that would have illuminated not only a major split between the two candidates, but a illustrated the major divide of the modern American political Left.

Instead, the moderators intervened to ask a question of Martin O’Malley, and shortly thereafter the network went to commercial.