Yearly Kos has managed to generate an impressive amount of controversy this year, but almost certainly no moment will be revisited as often in the next six months as Hillary Clinton’s strangely stalwart defense of lobbyist contributions.

As campaign gaffes go, it was huge.

Remember, this was not a debate before a gathering of insurance company CEOs. This was Yearly Kos: the world’s largest and most raucous venue for left-of-center bloggers and digirati.

Full-throated boos, especially in the age of YouTube, never play well, even when you’re defending something admirable.

But here Hillary was fighting for the inalienable right of the lobbyist to, you know, lobby.

Hard to believe, but she went there. And the last two days of coverage show that the moment will come back to haunt her in the primaries.

Now, the Clinton camp are no dummies. Far from it, and they will find a nice spin for this moment.

Best guess? They’ll eventually argue, quietly and off-the-record, that this was a Sister Souljah moment — a knowing public diss to a prominent Left-wing interest group — and that Hillary was deliberately showing her independence of any one interest.

Don’t you believe it: Hillary took a nasty tumble here, and the video below will show you the fall in excruciating detail.

But before you watch the video, there’s a passage I want you to read. The first time I watched this clip, something about Hillary’s early response to the lobbyist question jogged my memory, and I walked around all day trying to bring the connection to consciousness.

And then I had it: Hillary’s response reminded me almost exactly of a passage from Robert Reich’s Locked in the Cabinet, in which Reich describes preparing for his confirmation hearings as Secretary of Labor. Republican Senators are waiting their chance to get in their licks against Reich, and yet his handler tells him that under no circumstances should he attempt to actually answer a question.

Instead, Reich should feign humility, pretend to respect.

Here’s the passage where the handler coaches Reich on how to brown-nose the nasty Republicans.

“And” — he brings his face closer and looks me dead in the eye — “as often as you can say it without it sounding contrived, I want you to tell them how much you look forward to working with them. I look forward to working with you on that, Senator.”

“I look forward to working with you on that, Senator . . . .”

“G-o-o-o-o-d.” He smiles and is up pacing again. “And whenever you can do so without sounding like your nose is completely up their asshole, I want you to compliment them. Praise their leadership on the issue. Tell them you will need their help and guidance. Mention their years of diligence and hard work.”

I rehearse. “Senator, you know far more about that issue than I do, and I look forward to hearing your views in the months and years to come.”

“Wonderful!” he beams . . .

Now, with that passage firmly in mind, watch the video clip below. It’s the entire lobbyist sequence, posted originally at Talking Points Memo, not the abbreviated version that’s also making the rounds.