Jim Young / Reuters

Obscured by the recent avalanche of momentous news is this intriguing development from the campaign trail: The Hillary Clinton campaign now considers Bernie Sanders threatening enough to attack. Fresh off news that Sanders is now virtually tied with Hillary in New Hampshire, Claire McCaskill went on Morning Joe on June 25 to declare that “the media is giving Bernie a pass … they’re not giving the same scrutiny to Bernie that they’re certainly giving to Hillary.”

The irony here is thick. In 2006, McCaskill said on Meet the Press that while Bill Clinton was a great president, “I don’t want my daughter near him.” Upon hearing the news, according to John Heilemann and Mark Halperin’s book Game Change, Hillary exclaimed, “Fuck her,” and cancelled a fundraiser for the Missouri senator. McCaskill later apologized to Bill Clinton, and was wooed intensely by Hillary during the 2008 primaries. But she infuriated the Clintons again by endorsing Barack Obama. In their book HRC, Aimee Parnes and Jonathan Allen write that, “‘Hate’ is too weak a word to describe the feelings that Hillary’s core loyalists still have for McCaskill.”

McCaskill, in other words, is a great surrogate: someone eager enough to regain the Clintons’ affection that she’ll not only praise Hillary, but also slam their opponents. On Morning Joe, she had two talking points. First, journalists are giving Sanders a pass. Second, Sanders is a socialist, and thus can’t win. Asked about Sanders’ large crowds, McCaskill compared him to Ron Paul and Pat Buchanan, other candidates who sparked enthusiasm among their supporters but couldn’t win a general election because of their “extreme message.”

On point number one, McCaskill is undeniably correct: Media coverage of Sanders has been fawning, partly because many journalists harbor sympathy for his anti-corporate message but mostly because they’re desperate for a contested primary. Given Sanders’s strong poll numbers, the media would eventually have gotten around to tearing down the man they pumped up. But Team Clinton clearly wants to accelerate this process before Sanders gets any more momentum.

More intriguing is point number two. Sanders probably would be a problematic general-election candidate. But the liberals flocking to his side don’t much care. Nor are the Clintonites likely to scare off many liberals by reminding them that Sanders is a socialist. Most of them already know. And far from hiding it, Sanders is quite effective when challenged on this point. Right after he jumped in the race, George Stephanopoulos gave Sanders exactly the treatment McCaskill is calling for now. First, he reminded Sanders he was a socialist. Then, when Sanders pointed to Scandinavia as his socialist model, Stephanopoulos snarked that, “I can hear the Republican attack ad right now: He wants America to be look more like Scandinavia.” But Sanders was not cowed. “That’s right. That’s right,” he replied. “And what’s wrong with that? What’s wrong when you have more income and wealth equality? What’s wrong when they have a stronger middle class in many ways than we do?” It was the kind of performance more likely to leave liberals inspired than alienated.

McCaskill grew even less effective when Mark Halperin did something TV interviewers too rarely do: He demanded substance. Give “three specific positions” of Sanders that “are too far left,” he insisted. “I am not here to be critical of my colleague Senator Sanders,” McCaskill responded, absurdly. But Halperin caught her, noting that, “With all due respect, you already were: You said he was socialist and not electable.”

Then things got interesting. The specifics McCaskill offered were that Sanders “would like to see Medicare for all in this country, have everybody have a government-insurance policy,” that “he would like to see expansion of entitlement,” and that “he is someone who is frankly against trade.”

If Hillary actually goes after Sanders on these specifics, the Democratic race will get very interesting very fast. A debate about Obamacare versus single-payer health insurance, about expanding Social Security versus restraining its growth, and about the merits of free trade would be fascinating. But I doubt it’s a debate Hillary wants to have. She is, after all, running a campaign based on generating enthusiasm among the party’s liberal core. By taking bold, left-leaning positions on immigration, criminal justice, and campaign-finance reform, she’s trying (and so far succeeding) to erase her reputation from 2008 as a timid triangulator unwilling to offer big change. Yet the more Hillary emphasizes her opposition to single-payer health care, her opposition to expanding Social Security, and her support for free trade, the more she undermines her own strategy. By taking on Sanders on these issues, Hillary also implicitly takes on Elizabeth Warren, who has made expanding Social Security and opposing the Trans-Pacific Partnership two of her recent crusades.

The irony is that in 2008, when Hillary was trying to distinguish herself from her party’s left base in order to appeal to general-election moderates, an opponent like Bernie Sanders might have seemed like a blessing. In 2016, by contrast, when Hillary is running to the left, attacking him as too far left is dangerous.

No wonder McCaskill wants journalists to bury the curmudgeonly Vermonter. The Hillary campaign knows how tricky it will be to bury him themselves.

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