All these organizations were humming along at full capacity by the time Hillary Clinton won the nomination 12 years later. She had the full force of this “new progressive movement” squarely behind her.

And not only did Clinton lose anyway, but once again the party saw itself denied power in Congress and banished from statehouses. Last week’s election was 2004 all over again, only this time with a laughably unprepared opponent who had virtually nothing by way of campaign infrastructure at his disposal.

So what, exactly, do the great minds of the party tell themselves now?

There are plenty of culprits to fixate on. Already Clinton herself, and no doubt some of those around her, have blamed the FBI director, James Comey. There’s the predictable screaming about the undemocratic nature of the Electoral College, because apparently millions of Americans didn’t realize before last week that they weren’t living in ancient Athens.

In a New York Times op-ed, David Plouffe, who managed President Obama’s triumphant 2008 campaign, listed low turnout among younger and African-American voters as Clinton’s chief problem in states like Michigan and Wisconsin. Plouffe’s litany of causes came down to this: Donald Trump’s voters were super-excited about their candidate, and Clinton’s voters less so.

All of which certainly helps illuminate the tactical reasons Clinton lost, but not the larger, underlying problem.

Democrats lost because for a while now they’ve been telling themselves a story about modern politics. And while that story is comforting and has some significant truth at its core, it turns out to be dangerously wishful.

This particular story goes all the way back to 2002, when the writers Ruy Teixeira and John Judis published an influential book called “The Emerging Democratic Majority.” At a time when Democrats were dispirited, Teixeira and Judis argued, presciently, that the country’s demographics were evolving in ways that would ultimately favor their candidates.

As racial minorities and women came to encompass ever larger blocs of the electorate in the years ahead, and as the small-town South lost population to urban and western America, Democratic constituencies would inevitably gain a numerical advantage over traditionally conservative blocs.

This argument took on a special currency after 2004, when liberals (now calling themselves progressives) were busy building their new infrastructure. As changes in the makeup of the electorate began to accelerate, the theory of demography as destiny took firm hold on the left.

Basically, the party’s leading funders and operatives decided that they didn’t have to pander to white people living outside of cities anymore, because with each passing year their voters were cementing a new majority and redrawing the electoral map. Every election now was going to be a turnout election; get the people who already agree with you to the polls, and you don’t have to worry very much about persuading anyone else.

Barack Obama’s two elections seemed to them to validate this new Democratic math. Obama relied on a coalition of African-Americans and Latinos, along with first-time voters and women, to become only the fourth Democrat in history to break the 50 percent barrier — twice.

And so this was Hillary’s driving theory of the race. Her campaign was effectively nothing but a giant turnout operation, crunching data on reliable Democratic voters while simultaneously keeping the candidate herself from saying anything remotely interesting. She ran on a database, rather than on an argument; the more Trump alienated and motivated her base, the less she felt the need to make any discernible case.

I go back to August, when nothing much was happening in Clinton’s campaign, and I asked her to talk with me only about what her website said was her signature plan — a $270 billion proposal for infrastructure spending. Word came back that she wasn’t going to discuss it in any detail. To my knowledge, she never did.

It must be quite a relief, a warming feeling all over, to think you can win political campaigns without ever having to wrestle with complex subjects or talk to anyone who doesn’t already think you’re right.

But the Cult of Demography was built on some very flawed assumptions.

For one thing, it assumed that Obama was more or less a typical Democratic candidate, whose electoral math was now the party’s math. In fact, Obama was an anomalous, nontraditional candidate whose emergence inspired some traditional Democratic voting blocs — namely African-Americans and younger voters — in ways that no other campaign could hope to achieve.

According to exit polls, which are imperfect but the best measure we have, Obama won 95 and 93 percent of African-Americans, respectively, in his two elections. He won 66 percent of the youngest voters in 2008.

Clinton won 88 percent of African-Americans and trailed Obama among young voters by several points. You can say she “underperformed,” but the reality is that probably no other Democrat today could match what Obama did in these communities.

The second problem is that even if you buy that a Democrat can maximize turnout among minorities and the already converted, it doesn’t mean you can simply forget about everyone else. In politics, how well you do among your own constituencies isn’t all that matters; there’s also the question of just how poorly you do among the groups you can’t win.

An analysis by The Hill newspaper found that while Clinton actually performed better than Obama in the most densely populated counties of states like Pennsylvania and Michigan, she trailed him by much larger margins in the all-white rural areas, which sealed her defeat.

Why? Because she never so much as looked in their direction.

Obama was right to point out this week that he had made a concerted effort to reach rural white voters in 2008, if only to hold down his losses. I followed him then into Appalachian Virginia, where he was the first nominee of either party to show up in 32 years, and he and I talked about that focus at some length during the fall campaign.

According to excellent reporting by the New York Times’ Amy Chozick, no less a strategist than Bill Clinton himself argued to his wife’s campaign command that she, too, needed to speak to white working-class voters. No one listened. They were all about the database.

Of course, some Democrats will argue that even if this election doesn’t validate the demography argument, all they have to do is wait. They won the popular vote, after all, and those margins will only grow as America becomes more diverse and millennials more engaged.

They’ll point out that the share of white voters seemed to have declined by another couple of points this year, following a downward trend. Give it a few years, and Clinton’s model will work just fine.

But that’s making another dubious assumption — that because any bloc of voters is reliably in one camp today, they’ll still be there 10 years from now. It assumes that Republicans can’t field a candidate who appeals to some larger segment of black or Latino voters, a third of whom voted Republican this year.

It assumes, too, that younger voters don’t grow more ideologically diverse as they age. According to an analysis by the Democratic group Third Way, Gen Xers — my generation — grew markedly more conservative in the decade between 2000 and 2011. There’s not much reason to think millennials will remain stuck where they are, either.

The bottom line for Democrats ought to be this: You can’t really count on winning elections without persuading anybody of anything they don’t already believe. You can’t be a truly national party if you need 90 percent of a single minority’s votes just to be competitive (any more than you can be a national party relying only on white voters).

And you’re not going to put yourself back in the majority if your first reaction to Trump’s victory is to lash out at rural America as “rubes” or “deplorables.” That’s pretty much the opposite of solving your problem.

Democrats should find a new story in the months ahead. Because demography by itself isn’t actually destiny, and disdain isn’t much of a strategy, either.