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"If Trump wins (or comes close)," Vox correspondent Tim Lee writes, "liberals are going to need a better answer than writing half the electorate off as racist."

As the Democratic National Convention lurches off to a chaotic start, let me offer one answer: Hillary Clinton is a terrible, terrible candidate.

Don't get me wrong: Trump is a terrible candidate, too. Both of them have appallingly high unfavorable ratings, and enough name recognition that those unfavorables aren't likely to change all that much. But the Republican Party can at least say that their problem candidate was foisted upon them when a series of cosmically unlikely decisions by no-hope candidates split the party's normal factions just long enough for Trump to consolidate what was left over. The Democrats chose Clinton. Indeed, her party actively beat back alternatives, funneling all the money and the attention to Clinton, who brought all the well-known Clinton baggage with her, and sadly, did not bring any of her husband's charm, charisma or skill at working an audience.

Before I go on, I should stop and say: This is not about whether Clinton would be a good president. This is about getting to the Oval Office in the first place. We are not living under a parliamentary system where the party leadership can decide, after a brief internecine squabble, who gets to sit in the big chair. In American politics, you have to actually get elected. It's not enough to be effective at party politics, or even a wizard at policy. You have to actually be good at making people like you. Something that Clinton has never shown much aptitude for.

Being only middling likable myself, I'm certainly sympathetic. But you see, this is one reason that I am not running for president, and why, if I ever suggested such a daft thing, I would hope that the people around me would stage a tactful yet firm intervention. Instead, everyone around her rushed to enable her dream — and put the party in a position where it now has a real shot at making her the woman who lost the Oval Office, not just to Barack Obama, but also to Donald Trump, a man who clearly struggled over whether to distance himself from the Ku Klux Klan; a man who stage-managed his own convention into a series of own-goals, from his wife's plagiarized speech to the sight of a primary rival getting booed off the stage; a man who started off his post-convention campaign by rambling about a theorized connection between said primary rival's dad and the man who shot President Kennedy. Bill Clinton could have defeated Trump with one hand tied behind his back, a bag over his head, and a debilitating case of laryngitis. His wife is, at this point, struggling to hold even. I still think she's a favorite to win. But it never should have been close enough for anyone to care about the size of Trump's post-convention bounce.

Notice that I haven't even gotten to the e-mails — a story that broke in March of last year, the point at which it was still, if barely, possible for someone to sit down and say "for the good of the party, I'm afraid you need to develop a serious health issue that will require you to drop out of the race." Instead, the left half of the political spectrum solemnly agreed with themselves that this was a non-story, a three-day wonder, nothing for us to worry about. I am sympathetic to this decision only because by that point there was no one else, the entire machine of Democratic politics having been turned into a purpose-built vehicle for the Clinton candidacy. But why did the Democratic power brokers settle on Clinton back then? She could easily have ended up facing a much more viable opponent, like Scott Walker or Marco Rubio or John Kasich.

How can we explain this? For one thing, I think Clinton's candidacy — like Trump's candidacy, in its own, very different way — points to the fatal weakness of the political parties. Decades of "good government" reforms have systematically stripped the power that parties once had: to control money, to control committee assignments, to control how much pork politicians get to brag about to the voters back home. What's left is a hollow shell that cannot effectively respond to either grass-roots insurgencies or to outsize figures who effectively turn the party apparatus to their own ends. If you think, as I do, that parties play a vital role in organizing political action toward coherent goals and long-term accountability, that's something that should worry you.

My other working theory is simply that the left committed the cardinal sin known as "reading your own news releases." The left loved the "demographics is destiny" arguments that seemed to promise them a glorious future of uninterrupted rule. I cannot count the number of liberals who solemnly assured me that there was not going to be a Republican president in 2016, or any other year in the foreseeable future, because demographics.

These freelance demographers failed to note that these sorts of demographic predictions have been made before, and broken down before, as one or more solid demographic groups suddenly started switching to the other party. The true believers also tended to forget that these predictions were about the future. At this moment, those old white folks are still breathing, and voting.

So demographics don't guarantee a win. Neither did the Republicans' choice. She and Trump are in a dead heat. She'll almost certainly pull away again when she gets her own convention bounce. But again: It should never have been this close.

If Trump wins the presidency, there will be a lot of reasons, and a lot of blame to go around. But one factor, and some much deserved blame, will be the decision to anoint Clinton as the candidate long before the primary had even started. I don't blame Clinton for this, because upwardly mobile politicians like her all think they have what it takes to become president, and they do their utmost to get themselves into that coveted job. But there were a lot of people who ought to have known better. Either they didn't, or they didn't act on that knowledge. If Clinton doesn't manage to pull this out, that decision will haunt them for years to come.

Megan McArdle is a Bloomberg View columnist writing on economics, business and public policy.