Denis McDonough was White House chief of staff for President Barack Obama’s second term.

A proud Democrat troubled by the damage President Trump is doing to our country and our standing in the world, I welcome a spirited debate among our talented Democratic candidates as we decide who can replace Trump after next year’s election. As a veteran of the 2008 primary between then-Sens. Barack Obama and Hillary Clinton, I get that presidential primaries can get heated. But the debate we witnessed this week — where several candidates attacked one of the biggest assets Democrats have as we head into the 2020 election — was a missed opportunity.

The news out of Wednesday night’s Democratic debate was not a series of hopeful alternatives to a manifestly weak White House but rather several candidates attacking former president Obama’s record. Now, I recognize some of this is just trying to get traction against the front-runner, former vice president Joe Biden. But it actually doesn’t make any sense, politically or substantively.

First, Obama remains widely admired, with a 95 percent approval rating among Democrats and 61 percent among independents, which is why he will likely be asked to campaign fiercely for our nominee. As in 2018, he will be able to use his unique public standing to help Democrats win in 2020.

Second, he is admired not only for what he did in the White House but, in great contrast to the current president, for how he did it.

The party, and country, is in an entirely different place than we were in 2008. It would be stale and outdated to run on the same ideas, plans and policies that Obama advocated and accomplished. But it would be equally wrong to miss the chance to build boldly off that record, grounding new policies in reality.

On foreign policy, Obama restored the United States’ leadership in the world after the Iraq War, rebuilt our alliances, delivered justice to Osama bin Laden, united the world to contain Iran’s illicit nuclear program and, in establishing the first truly global climate agreement, ensured China, the world’s largest polluter, for the first time would be bound to meet limitations on climate-changing carbon pollution in the same way as every other major economy.

On the economy, Obama managed us out of the deepest recession since the Great Depression and led to 75 straight months of job growth. And, as economist Jason Furman has shown, Obama enacted tax changes that “resulted in a larger shift of income to the bottom 99 percent of households than the tax changes of any Administration since at least 1960.”

On immigration, Obama proposed far-ranging changes to immigration laws, and when those reforms were stopped by Republican intransigence, he used executive authority and enforcement priorities to emphasize keeping families united while deporting people convicted of crimes and new undocumented arrivals who were not in the asylum process. Unless the United States opts for open borders, there will be deportations — whether you call the actions civil or criminal. If any of the candidates would have different enforcement priorities, they should say so. Not one of them has.

And, perhaps most important, on health care, Obama dramatically expanded access to coverage, reducing the rate of uninsured by half — a great start. The Affordable Care Act should have a public option and more generous subsidies to cover everyone, but it is a grievous mistake for any Democrat to walk away from a historic generational reform that has brought coverage without regard to preexisting conditions, free preventive health care and substance abuse treatment and mental health treatment to more than 20 million people.

This election is not about Obama. He has said over and over again that our progress is never complete. That the whole point of democracy is to make as much progress as you can before handing it off to the next generation. Restoring the United States’ leadership position in the world is progress. Igniting a clean energy revolution and getting the entire world to agree to lower emissions is progress. Maintaining our historic commitment to immigrants, asylees and refugees is progress. And halving the uninsured rate in one fell swoop is progress. These accomplishments are what makes it possible to take the next step. And because Obama got us this far on so many issues we care about, it is up to the Democratic candidates now. As he said in his farewell address in Chicago, “but for all the real progress that we’ve made, we know it is not enough. . . . All of us have more work to do.”

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