Republican presidential nominee Donald Trump and Democratic presidential nominee Hillary Clinton at the second presidential debate at Washington University in St. Louis on Oct. 9, 2016. (Jim Young/Reuters)
Contributing columnist

An internecine Democratic spat broke out last week when a January comment from Pete Buttigieg resurfaced criticizing Hillary Clinton’s 2016 campaign. Buttigieg said President Trump had (albeit in a “twisted way”) at least “pointed out the huge troubles in our economy and our democracy,” while Clinton had gone “around saying that America was already great.” This assertion drew strong rebukes from Clinton spokesman Nick Merrill and ex-Democratic National Committee chair Howard Dean. This was not the only shot that Buttigieg has taken at Clinton’s 2016 campaign.

Clinton supporters are understandably touchy about such critiques: Clinton won nearly 3 million more votes than Trump in 2016, and unless your name is Barack Obama, you haven’t come close to winning the number of votes she has. And while she did run some social media (and sold hats) that touted America’s greatness in 2016, it is unfair to imply that Clinton ran on complacency: Her proposals for change were the most ambitious of any Democratic nominee since Franklin D. Roosevelt.

But if Clintonites (and I am one) do not like others criticizing her 2016 campaign, it is on them to identify what we should have done better. The campaign ended in defeat. And while evidence suggests Clinton would have won if not for Russian meddling and then-FBI Director James B. Comey’s bumbling, Democrats might have to overcome a similar deus-ex-Trumpica in 2020. What’s more, Trump will be an incumbent this time. Thus, our nominee in 2020 must outperform the 2016 Clinton campaign, plain and simple. Here is my list of three places to start.

First, never doubt that Trump can win. To be clear: The Clinton campaign did not take Trump lightly or take victory for granted. But many of us believed the United States would never elect someone as unfit, unstable and hateful as Trump, and surely that colored some aspects of the campaign, even if only subliminally. We know that it impacted others: Comey has said his unprecedented actions were based in part on his assumption that Trump would lose, and it seems likely that some of Trump’s press coverage was similarly affected by the assumption that he would be good for ratings in October but gone by November.

Let there be no doubt in 2020: No matter what the polls indicate and no matter what the Mueller report or prosecutors in New York ultimately say, Trump is the incumbent, and incumbents (absent war or economic calamity) usually win. Everyone involved in the 2020 campaign needs to start there.

Second, a collection of policy proposals is not the same thing as a vision that voters find compelling. I’ve never worked in a campaign — including 1992 and 2008 — that had policy proposals as well developed as Clinton’s. And yet, they never quite connected with voters. “Debt-free college” confused many; a $500 billion infrastructure plan was smaller than Trump’s and yet too expensive in others’ minds; a “financial risk” fee was a smart way to address inequality but not particularly evocative to the left behind. And perhaps most of all, the sum never became more than the whole of the parts. Policy pointillism didn’t create a persuasive overall portrait.

There is a warning here for 2020 candidates. Many have set forth impressive, elaborate policy proposals. But do these plans inspire a call to action? Moreover, even voters drawn to Clinton’s policy proposals did not believe she could get them passed. Candidates in 2020 cannot just run on plans for change; they need to articulate a theory by which — at a time of brutal partisanship — they can achieve it.

Third, no matter what facts and figures say about “recovery,” this remains an angry country deeply scarred by the 2008 economic collapse. All the objective data pointed to economic optimism in 2016, and as an ally of the sitting president, Clinton was forced to run on a positive message (as were Al Gore in 2000 and John McCain in 2008). Historically, in presidential campaigns, the more optimistic candidate almost always wins. But not in 2016. Even with unemployment down and growth up, voters were angry and did not feel as if they had “recovered.”

For Trump, that anger — then and now — centered not on economics but on cultural resentments: antipathy toward immigrants, people of color, the news media, “coastal elites.” Democrats in 2020 need to build a different coalition of the angry — anger about income inequality, discrimination, climate change, health care, a lack of accountability — that goes beyond animus toward Trump and his corruption. Fire need not be mean-spirited; it can be done with open arms for potential allies and graciousness toward opponents — as Rep. Alexandria Ocasio-Cortez (D-N.Y.) recently showed in an MSNBC town hall. But it must be part of Democrats’ DNA in 2020 if they want to win.

Others will have different items on their “to improve” lists — some tactical, some technical. But while no 2020 Democrat should campaign on a critique of Clinton’s 2016 effort, anyone who wants to see Democrats win this time should embrace an honest conversation about how our nominee can improve on it.