Bernie Sanders’s strong campaign is solving Hillary Clinton’s biggest problem

Thursday night’s Democratic debate started out with an electrifying — and rare for Democrats — series of frank back-and-forth blows over ideological questions. Bernie Sanders said the big problem with Hillary Clinton is that she is, in her own words, a moderate.

“Nothing is wrong with being a moderate,” Sanders said, but “you can’t be a moderate and be a progressive.”

Clinton shot back with a double-barreled assault, arguing that on the one hand Sanders’s definition of real progressive values would rule Barack Obama, Joe Biden, and Paul Wellstone out of the progressive circle. On the other hand, she charged that Sanders himself couldn’t meet the test of full ideological rigor.

“I don’t think it was progressive to vote against the Brady Bill,” she said, “I don’t think it was progressive to vote against Senator Kennedy’s immigration reform.”

Yet the reality is that no matter how annoying Clinton, her team, and the dozens of senior party figures backing her may find it, Sanders’s attacks are in Clinton’s long-term best interest. That’s because his framing of Clinton as a temperamentally cautious, ideologically moderate politician who tries to straddle the divide between progressive activists and status quo business groups is, for better or worse, exactly how she is going to want to portray herself for the coming general election.

After all, though this is obviously not what most of the Democratic Party base wants to hear, there’s simply no evidence that the mass public in the United States is eager to mobilize on behalf of Sanders’s vision of a drastic policy lurch to the left.

On the contrary, as Lynn Vavreck and John Sides show in The Gamble, their excellent book on the 2012 campaign, voters saw themselves as ideologically between Obama and Mitt Romney but closer to Romney.

One thing this shows is that there’s a lot more to winning an election than ideology. The economic fundamentals in 2012 favored Obama, and voters may have understood that with Congress in Republican hands, conservative overreach was more of a practical worry than liberal overreach.

But where ideology is a factor in elections, this data shows that voters are likely to prefer a moderate Democrat, like Sanders says Clinton is, to a more left-wing one, like Sanders says he is. Clinton’s specific arguments against Sanders on the progressive question were not necessarily so convincing — it’s clear that with the exception of guns, he is a uniformly more left-wing politician. But given that she is very likely to be the nominee, it’s likely in her interest to lose this argument to Sanders. A moderate is a good thing to be.

The standard trade-off with this kind of thing is that moderate positioning that helps you in the general election will hurt you in the primary. But in this case it’s really not so clear. Democrats are clearly the more liberal of the two parties, but the party itself is split about in half between voters who consider themselves liberal and those who don’t.

Highly educated Democrats and white Democrats tend to be very liberal, which is why Sanders did well in Iowa and is poised to do very well in New Hampshire. But when the campaign heads to the South and West, where the electorate gets more diverse, he will find voters who simply don’t prize ideological consistency the way he does.

Throughout almost the entirety of 2015, the Democratic Party acted as if it were terrified of having a real nominating contest. Party leaders uniformly lined up behind Clinton and made sure that other major contenders like Elizabeth Warren and Biden stayed out of the race. Clinton was left to face a field largely composed of lovable eccentrics — Jim Webb, Lincoln Chafee, and Sanders — and given a short series of debates scheduled for odd weekend time slots when few people were likely to watch.

Then, against insiders’ expectations, Sanders proved to be a formidable candidate. His unabashed progressive politics has been viral on social media and resonated deeply with young people. He even started to pose enough of a threat to Clinton that she decided she wanted more debates after all. The result was an excellent duel between the two of them that we saw Thursday night.

It’s a duel that Clinton is somewhat less likely to win than the “coronation” Democrats tried to arrange for her. But if she does win the nomination, she’ll come out a stronger and healthier candidate for having gone through the trouble of actually facing down criticism from the party’s left wing. Primary campaigns can get ugly, but they’re fundamentally healthy and Democrats were wrong to be so fearful of having one.