Megan McArdle is a Bloomberg View columnist. She wrote for the Daily Beast, Newsweek, the Atlantic and the Economist and founded the blog Asymmetrical Information. She is the author of "“The Up Side of Down: Why Failing Well Is the Key to Success.” Read more opinion SHARE THIS ARTICLE Share Tweet Post Email

Photographer: Joe Raedle/Getty Images Photographer: Joe Raedle/Getty Images

The most electric moment of last night’s Democratic debate was when Bernie Sanders declared that he was sick of hearing about Hillary Clinton’s e-mails. The sentiment clearly resonated with the audience, and it was therefore smart politicking on the part of Sanders, who is not going to win himself more primary votes by pursuing subjects that make the Democratic base mad.

And yet while this may be good for Sanders, it’s probably bad for the Democratic Party. This morning’s declarations that Clinton “nailed it” and emerged as the clear victor may or may not be correct. But those declarations came from a genuine observation, that Hillary Clinton did not visibly stumble -- except in answer to one question: whether she considers herself a moderate or a progressive.

Her difficulty with this question tells you that politicians on both sides of the aisle, not just the Republican side, are now afraid to be seen as moderates. Gone are the days of pitching yourself as a “New Democrat” or a “compassionate conservative”; the base wants full-throated declarations of eternal fidelity. Democrats who have been gloating over the intransigence of Republican Party factions should probably prepare for similar battles between pragmatism and purity in the nearish future.

What you did not see on stage, however, was all-out attacks on the front-runner, as you have seen from the Republican side. This makes eminent political sense: Clinton is the probable nominee, which makes it unwise to anger her, and no one else has a sufficiently large following to risk the ire of the base by attacking someone whose approval rating remains high among Democrats. However, this has the effect of making Clinton look stronger than she is.

This has been the story of her career in politics: she has a lot of experience in government, but very little in campaigning for herself. The one time she played against a varsity team, she lost to Barack Obama. In her only successful campaign, she was ushered into Pat Moynihan’s Senate seat by the senator himself, running as the Democratic heir-apparent in a deep-blue state, and facing a Republican opponent of truly startling ineptitude.

Can Clinton survive a race against a more gifted campaigner, in a nation with considerably more conservatives than New York has? Now would be a good time for Democrats to find that out. At least Democrats could see how she performs under pressure from politicians who are out for blood. Instead they mostly treated her like a delicate aunt whose ears must be protected from harsh words.

Lincoln Chafee’s attempt to bring up the e-mail issue was probably the closest they came to the sort of slings she will suffer in the general election campaign, but it was not very close, since he delivered this with the frightened determination of a second-grader given his first speaking role in the Christmas play.

Yet Clinton needs to practice taking punches now, because rest assured, she will be taking a lot of them before November of next year. The no-hopers on stage would have done a service to their party and Clinton if they had tried to land a few blows. But instead they danced around, and so the electorate will have to wait to find out whether Clinton can hit the ropes and come back fighting.

Unfortunately for Democrats, if she can’t, it will then be too late to do anything but gape from the sidelines.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.