Organizers of last week’s Bloomberg/Washington Post Republican presidential debate almost pulled off a coup in modern polemical staging. Thanks to strong audience management and a finely supervised debate format, they confined the discussion to the candidates themselves. Probing questions, interesting responses — civil discourse.

Until the waning minutes, that is.

That’s when some guy started shouting, heckling at the stage. From where I sat — in front of a streamed broadcast on, that is — the man’s words were beyond comprehension.

Wrote @EdMorrissey on Twitter: “Pretty sure heckler was yelling at Santorum about his answer to the gay soldier in the previous debate.”

The outburst earned the man expulsion from the venue, according to a Bloomberg spokesperson.

The rudeness kept an episodically shameful yet often entertaining streak alive. All of the post-Labor Day Republican debates this year have featured noteworthy moments of audience participation or heckling. The NBC/Politico debate had the audience applauding Rick Perry’s record of executions in Texas; the CNN/Tea Party Express had a few stragglers applauding the hypothetical death of an uninsured man; the Fox/Google debate had an audience member or two booing a gay soldier for . . . existing.

Pressure is high, accordingly, on CNN and the Western Republican Leadership Conference to stage a heckle-free event tonight in Las Vegas. The debate will be held at the Venetian Resort-Hotel-Casino. An audience of 1,500 will watch the proceedings.

Now, who will those 1,500 people be? That’s not too clear. According to CNN, the network and the Western Republican Leadership Conference are sharing distribution rights for the tickets. It’s “invite-only,” according to a CNN spokesperson.

Any special precautions to keep the onlookers in check? “We ask for the audience to be cordial and hold their applause, not to engage in the debate itself,” says the spokesperson. Uh-oh. As noted above, such a strategy hasn’t worked too well in previous sessions.

Organizers, of course, can do only so much to stop outbursts. Real responsibility for this rashness rests with the candidates themselves, who say enough ridiculous things that qualify as heckles.

What, after all, is the difference between a heckle and Michele Bachmann telling a questioner that he should be able to keep every dollar he earns? What’s the difference between a heckle and Rick Perry saying he doesn’t lose any sleep over the possibility that a fallible criminal justice system could have killed innocent people in Texas? And what’s the difference between a heckle and Ron Paul saying that a border fence could be used to keep United States citizens cooped in?