The document for which Mark Penn will be remembered in books documenting the nation’s political history is a memo he wrote for Hillary Clinton’s 2008 presidential primary campaign. That memo argued that Clinton — for whom he was an adviser — should focus on blue-collar voters and women, taking pains to note that, unlike Barack Obama, she was born in the middle of the United States.

“Let’s explicitly own ‘American’ in our programs, the speeches and the values,” Penn suggested, saying that Obama’s diverse, multicultural background should be saved “for 2050,” when the nation itself was more pluralistic. “Let’s use our logo to make some flags we can give out. Let’s add flag symbols to the backgrounds.”

Obama was unelectable in a general, Penn argued, except “perhaps against Atila [sic] the Hun.”

That turns out to have been wrong.

If that memo didn’t exist, Penn’s essay at the Hill published on Thursday might be considered one of his more problematic pieces of analysis.

We can’t fault Penn too much for the headline — “Why the polls are still wrong” — as it’s rarely the contributor’s choice what the headline will be. But it’s remarkable that Penn didn’t ask that the headline be changed, given that his entire point is that polls show President Trump with more support than he’s given credit for, albeit in the form of support for his stated policies. A dozen polls are cited in service to an article summarized as “the polls are still wrong.”

Regardless, we can certainly fault him for his arguments.

It’s true both that Trump is broadly unpopular (as measured by multiple opinion polls) and that there are positions he espouses that are popular. We will cede that since, well, it’s sort of obvious. We will also cede the point that Republicans broadly think Trump is doing a good job, something that has been noted any number of times by The Washington Post and others.

As Penn makes that point, though, he goes out of his way to include weird cultural touchstones that seem clearly intended to appeal to that Trump base.

For example, this is how Penn dismisses polling that shows Trump as unpopular:

The methodology of some of these polls is to poll “all adults” without any qualification as to citizenship or voting intent. A lot of the nonvoters dislike politics and all politicians, and these polls also include them along with undocumented immigrants who are not screened out.

There are two implications here. The first is that somehow people who don’t vote don’t get to have an opinion on the president. The second is that the number of people who reject the president is swollen by undocumented immigrants. At most, undocumented immigrants represent 3 percent of the population, a group that’s less likely to speak English and almost certainly not registered to vote. To suggest that they make up a significant portion of the responses to a poll is disingenuous.

“The president gets 65 percent approval for hurricane response and 53 percent approval for the economy and fighting terrorism,” Penn writes as he fleshes out “a more complex picture” of opinions on Trump. “He gets his lowest marks for the way he is administering the government. And he is a divider when people want a uniter.”

This is deliberately playing down how low Trump’s numbers are.

Trump’s hurricane response — measured before his response to Puerto Rico — is one of the few bright spots for him. Different polls show a broad range of opinion on the economy, although he usually does decently on it. (In The Post’s most recent poll, more people view him unfavorably than favorably on this metric.) Penn leaves out a host of other issues where Trump consistently fares poorly, including immigration and health care. He doesn’t mention a number of personal characteristics, on which Trump is generally viewed negatively. It’s cherry-picking.

Then there’s this paragraph, which follows one about Kim Jong Un.

Iran’s national anthem is “Death to America,” and no one is taking a knee to that one over there. The regime once held our embassy hostage, and 70 percent of America believes it will cheat on the nuclear arms deal. So senators who attack Trump for being too tough on these known despots and killers may get a lot of coverage but are swimming upstream, giving indirect comfort to our fiercest enemies.

What on Earth is that? The “take a knee” thing is an out-of-the-blue shot meant to question the patriotism of those NFL players participating in protests during the national anthem. But then Penn implies that majority belief that Iran will cheat on the nuclear deal will mean a political cost for senators “who attack Trump for being too tough on these known despots and killers.”

First of all, it’s not clear how that out-of-context data point applies to assessments of Trump’s “toughness.” The poll result suggests that people would support Trump, say, taking steps to make sure Iran doesn’t cheat on the deal, but not much more than that.

Second: Who are these so-called senators? What senator has said, “Trump is being too tough on Iran and Kim”? None, of course. Many have criticized Trump’s handling of those two foreign policy issues for a variety of reasons, but I challenge you to find an example of a senator asking Trump to take it easy on them. It’s a straw man meant to make Trump’s position seem both more sound and more defensible.

Penn insists that Obama was popular while his policies weren’t while the opposite is true for Trump. To make this point, he deliberately reframes Trump’s policies, suggesting that Americans want more border security. Sure. Trump’s go-to answer for that is to build a wall — which is a deeply unpopular proposal.

More important, Penn ignores the core issue at play: partisanship.

Republicans opposed Obama and his policies fervently and Democrats supported them, leading to mixed opinions. The reverse happened with Trump, including actual partisan flips on some of the same policies. Penn’s response to Trump’s polling? We need to pay more attention to that strong Republican support.

In some cases, Trump’s positions are more popular because he took the position, as with the NFL protests. That’s his base reading his pulse, not necessarily him reading the pulse of the nation.

Why did Penn write his piece? It’s not clear, but the undercurrents are revealing. He is clearly sympathetic to Trump, a guy who ran the campaign that Penn wanted to see from Clinton in 2008. He likes to play the contrarian. And he’s going out of his way to lure Trump supporters to his cause.

If you want to believe that the polls are wrong and Trump is generally popular, feel free. But Penn’s analysis shouldn’t convince you that’s true.