Democratic primary voters are being asked to consider a dizzying number of presidential candidates, and it must be difficult to sort and prioritize their various policies and records. Brad DeLong, a distinguished economist, former economic adviser to the Clinton and Obama administrations, and author of a feisty blog, suggests one standard: Do the candidates have a clue about the lessons of the Obama years?

DeLong, a self-confessed “neoliberal shill” and “Rubin Democrat”—a reference to Robert Rubin, former Goldman Sachs head, big Democratic donor, Clinton Treasury secretary and Obama mentor, and Citibank executive disgraced in the financial collapse—created a stir when he admitted that his set had gotten it all wrong. “The baton rightly passes to our colleagues on our left,” DeLong wrote. “We are still here, but it is not our time to lead.”

There are two parts to DeLong’s mea culpa. The first, which is mentioned only in passing (but elaborated in his blog and his writings), is that they got the economics wrong. Markets do not self-regulate, as the financial collapse proved. GDP growth does not solve the question of growing and extreme inequality. Unprecedented and continuing trade deficits—particularly with one country, China—do have savage effects, even if consumers get cheaper goods. Austerity kills, and the threat of runaway inflation is vastly inflated. “The world appears to be more like what lefties thought it was than what I thought it was for the last 10 or 15 years,” deLong wrote.

The second is that “we were certainly wrong, 100 percent, on the politics.”

The Obama mindset assumed that if the administration compromised preemptively, responsible Republicans would support market-friendly reforms, such as the Affordable Care Act. Forging a broad bipartisan coalition would ensure that the reforms are “more strongly entrenched” than if implemented by a “narrow, largely partisan majority.”

“Barack Obama rolls into office with Mitt Romney’s health care policy, with John McCain’s climate policy, with Bill Clinton’s tax policy, and George H.W. Bush’s foreign policy,” DeLong points out in an interview with Vox. “And did George H.W. Bush, did Mitt Romney, did John McCain say a single good word about anything Barack Obama ever did over the course of eight solid years? No, they fucking did not.”

Efforts to gain Republican support only weakened and delayed desperately needed reforms when Democrats controlled both houses of Congress with the economy in free fall after the financial collapse. Efforts to assuage conservative opinion—as in Obama’s premature turn to “tightening our belts” and a “grand bargain” on Social Security and Medicare with unemployment still in double digits—only confused allies and misled people.

Republicans thus benefited from scorched-earth obstruction. By the end of the Obama years, Democrats lost control of both houses of Congress, dozens of state legislatures and governors’ offices, and, in the end, got Donald Trump in the White House.

DeLong argues that you simply can’t ignore this failure. “Today, there’s literally nobody on the right between those frantically accommodating Donald Trump, on the one hand, and us on the other…. There’s simply no political place for neoliberals to lead with good policies that make a concession to right-wing concerns.”

“We tried to do health reform the Republicans’ way and what’s now clear with a Republican Supreme Court and with a lot of Republican governors, any attempt to do it the Republicans’ way is going to get shredded. We tried to do climate policy the Republicans’ way and got nowhere,” he says.

Democrats have to change. Instead of piecemeal reforms designed to gain Republican support, Democrats, DeLong argued, should lead from the left, forwarding bold and fundamental reforms.

“Until something non-rubble-ish is built in the Republican center, what might be good incremental policies just cannot be successfully implemented in an America as we know it today. We need Medicare-for-all, funded by a carbon tax, with a whole bunch of UBI rebates for the poor and public investment in green technologies.”

The DeLong standard applies directly to the current debate among Democratic presidential contenders. Polls suggest Democrats traditionally value bipartisan cooperation more than Republicans, although that has changed under Trump. Pundits like the ever-sonorous David Brooks lavish praise on Democrats who could bring us together. Voices calling for unity and reason appear like ports of shelter from the Orange Menace.

Obama is immensely popular among Democrats. We miss his eloquence, his decency, his intelligence and grace. DeLong, however, offers a reality check: Obama’s signature efforts to rise above politics, to reach across the aisle, were greeted with a closed fist.

That suggests a standard for the coming presidential debate: Who has learned the lesson from the past? Clearly, those candidates who argue that the path to change is bipartisan cooperation are simply in denial. When Joe Biden and Senator Amy Klobuchar suggest that they have the relationships that can reach across the aisle to create pragmatic reforms, or Beto O’Rourke or Governor John Hickenlooper suggests that they can bring us together, they are peddling what polls well, not what makes sense.

The DeLong Standard requires only that a candidate not be in denial of the central lesson of Obama’s presidency, as Pete Buttigieg puts it, that “any decisions that are based on an assumption of good faith by Republicans in the Senate will be defeated.”

Candidates will draw different conclusions from this reality. Sanders and Warren clearly adopt what might be called the Reagan strategy: Run as a movement candidate with a clear, bold agenda, rouse people in support with a focus on core economic rights, and win with a mandate. Sweep others into office at all levels and begin what Sanders calls the “political revolution.” Reagan inaugurated a fundamental turn to the right by defeating an incumbent president, Jimmy Carter, and picking up 12 Senate seats for their first majority in 28 years, and 34 House seats. While Republicans didn’t have a majority in the House, Reagan’s sweeping victory so intimidated Democrats that they gave him a good part of his core agenda.

Buttigieg, whose web page is thus far literally devoid of any policy proposals, suggests that the answer is a focus on institutional reform—ending the filibuster in the Senate, getting rid of the Electoral College, adding six members to the Supreme Court. By making institutional reforms a centerpiece of his campaign, he similarly hopes to gain the mandate to get them through the Congress.

In any case, DeLong sets the threshold: Denial of political reality—no matter how well it polls—isn’t “pragmatic,” it’s fanciful. Candidates who don’t understand that don’t have a chance of leading the change we need.