Even after her New Hampshire collapse, Clinton still has significant advantages, particularly predominant support among minority voters. But if Sanders continues to drive the campaign argument, those defenses will face increasing strain.

The Sanders team, in fact, believes it has boxed Clinton into an intellectual corner. If she portrays Sanders’s agenda as unrealistic, they believe they can accuse her of limiting Democratic ambitions only to the ideas acceptable to the Republican Congress. If she attacks Sanders’s ideas head on, they believe she will be forced to adopt conservative critiques that grate on most Democrats.

Is there a way out for Clinton? The answer might be found in Bill Clinton’s 1992 campaign. With his “New Democrat” agenda, Bill Clinton squarely confronted the idea that only ideologues could offer big change. Instead, with ideas like welfare reform and national service, he insisted that it was possible to both reinvigorate and reform Washington and to reconcile government activism with fiscal discipline.

Hillary Clinton faces a tougher puzzle than her husband did because the Democratic coalition has grown more liberal since his day (with Millennials and minorities replacing older and blue-collar whites.) But, even so, the Clinton campaign appears overly pessimistic about its ability to challenge Sanders over his agenda, or to rally Democrats around an alternative case for widening opportunity without lurching to the left.

By Sanders’s own calculations, his program would increase government spending by $1.7 trillion annually. That’s roughly a 40 percent increase over today’s federal budget. Sanders’ universal single-payer health care program (at $1.4 trillion annually) accounts for most of that increase, but he would also devote about $300 billion ever year to ideas like free public college tuition, more Social Security benefits and an ambitious infrastructure program. Sanders’s calculations don’t even include his plans for expanded pre-school and day care, which could push his program’s yearly cost toward $2 trillion (even before considering whether he has lowballed his health plan’s cost, as some analysts argue). If his entire program were implemented, federal spending as a share of the economy would soar to easily its highest level since World War II.

It doesn’t require parroting Paul Ryan to ask whether the economy can absorb that big an increase in federal expenditures (even with the savings in private health insurance premiums Sanders’ plan would create). Or to question whether the federal government could spend that much more money effectively—especially without the kind of reform agenda that Bill Clinton championed. "It's easy to promise to make government bigger or smaller,” says Bruce Reed, Bill Clinton’s chief White House domestic-policy adviser. “At a time when Americans are fed up with all the institutions that have failed them, it's much bolder… to make government and Washington work."