Hillary Clinton's supporters have yet to make a persuasive case that Sanders is too great a risk.For the better part of a year, Bernie Sanders enjoyed a polite if slightly bemused welcome from the non-radical quarters of the Democratic firmament. The wing of the party represented by Sanders and Elizabeth Warren had been ascendant for most of Barack Obama’s presidency, enlarging the potential constituency for a populist presidential primary challenge to Hillary Clinton. As a grumpy-yet-affable elderly Jewish socialist who wasn’t actually a Democrat, Sanders struck members of the liberal establishment as the least-viable tribune of the party’s insurgent wing.
One week from the Iowa caucuses, we now know their assessment was wildly inaccurate. Sanders is within striking distance of Clinton in Iowa, and leads her in most New Hampshire polls. He still trails badly in more ethnically diverse Southern and Western states, but the Clinton campaign and its allies are suddenly contending with the possibility that Sanders will convert victories in both of the first two contests into polling surges elsewhere in the country, imperiling Clinton’s nomination, or at least making her path to it much longer, costlier, and more divisive.