Plenty of postmortems of the 2016 presidential race have dwelt upon the roles of Russia, James B. Comey and myriad other plausible causes of President Trump's win. But MSNBC's Chris Matthews seems to think one major contributor has gotten short shrift: Hillary Clinton's labeling of Trump's supporters as “deplorables.”

While giving a talk on his new book at the Miami Book Fair this weekend, Matthews suggested that Democrats as a party have alienated white working-class voters by talking about them sneeringly.

“You know, ever since we started this Archie Bunker thing in the early '70s, making fun of white working people, we kissed them goodbye,” Matthews said. “You make fun of people, you look down on them? They get the message. You call them 'deplorables'? They hear it. You bet they hear it. You say they cling to their guns and their religion? 'Oh yeah, I cling to my religion. Okay. I’m a little person, and you’re a big person. Thank you. I’ll be voting for the other guy this time.' "

While Mitt Romney's "47 percent” comment remains the consensus Reason He Lost in 2012, Clinton's “deplorables” comment isn't so widely regarded as a major gaffe — much less one that cost her the election. But for Democrats conscious of trying to return their party to its winning ways in states such as Michigan, Pennsylvania and Wisconsin that swung for Trump, it's an extremely important question.

What we can say is this: There is a credible case to be made that Clinton cost herself with her “deplorables” argument.

This is the point in this post at which many of Clinton's most passionate supporters will become apoplectic. They will argue that racism and misogyny need to be called out at any cost. And they 100 percent have a point that Trump has stoked cultural resentment and has walked into racial controversies way too many times to believe it's just a coincidence. (The week is less than two days old, and he's already feuding with a black athlete and the black father of another athlete.) His base strategy has been among the most bare-knuckle we've ever seen in politics, recalling the “Southern Strategy” for which some in the national GOP have apologized.

But there is a moral argument, and then there's a political argument. And even Clinton has acknowledged — both during the campaign and since — that it wasn't a good moment for her. There is also polling to back up the idea that it worked against her.

In her initial comments on Sept. 9, 2016, Clinton said if you were being “grossly generalistic, you could put half of Trump's supporters into what I call the 'basket of deplorables.' " She defined being a deplorable as being racist, sexist, homophobic, Islamophobic and/or xenophobic.

Soon, Clinton was backing off the “half” part. “That was wrong,” she said. But she stood by her general sentiment.

A Washington Post-ABC News poll conducted a week and a half after Clinton's “deplorables” comment showed that nearly two-thirds of voters felt it was unfair, even as revised. Sixty-five percent said it wasn't fair “to describe a large portion of Trump's supporters as prejudiced against women and minorities.”

This included nearly half of Democrats (47 percent) and two-thirds of independents (68 percent).

The comments also might have registered in head-to-head polls. While Clinton led in the Real Clear Politics average of polls by 2.7 points Sept. 9, by Sept. 18 her lead had slipped to less than a point. This would wind up being her smallest lead of the entire general-election campaign.

Isolating one factor as the cause of that shift over a nine-day span is difficult, especially given other things that happened during that period that also could have had an impact. Just as the tightening in the polls after James B. Comey's disclosure of more Clinton emails with 11 days to go can't be completely isolated, neither can this.

But for a Democratic Party whose loss clearly owed to a shift among a very specific demographic, it's worth entertaining the idea that the comment Matthews highlighted — and the general attitude that fed into it — could have played a role.

Clinton, for what it's worth, acknowledged on her recent book tour that the deplorables comment was a “gift” to Trump, while downplaying its significance. “I’m sorry I gave him a political gift of any kind, but I don’t think that was determinative,” she said.

Yet as with every other potential cause of her loss, if it shifted just 80,000 voters in Michigan, Pennsylvania and Wisconsin, then it could have been.