It’s not the official DNC debate for September, but it’s a national platform nonetheless. CNN will hold a town hall in the first week of September to discuss the “climate crisis,” and all of the top-tier Democratic presidential hopefuls have committed to being on stage. All but one, that is, as CNN notes in its (understandably) buried lede:

Nine Democratic candidates for president have qualified for next month’s Climate Crisis Town Hall, which will air exclusively on CNN platforms, and eight of them have said they will participate.

CNN is devoting the evening of Sept. 4 to the climate crisis. Eight of the Democratic candidates have accepted CNN’s invitation to discuss this critically important issue: former Vice President Joe Biden; Sen. Cory Booker of New Jersey; South Bend, Indiana, Mayor Pete Buttigieg; Sen. Amy Klobuchar of Minnesota; former Rep. Beto O’Rourke of Texas; Sen. Bernie Sanders of Vermont; Sen. Elizabeth Warren of Massachusetts; and businessman Andrew Yang.

Citing a scheduling conflict, Sen. Kamala Harris of California declined CNN’s invitation.

A scheduling conflict? What kind of event on Harris’ schedule eclipses a nationally televised event at which all of her main competitors for the nomination will be present? The only person in the field that might afford to coast past this event would be Joe Biden, whose polling numbers put him more than ten points over his closest competition. (Biden’s skipping a California Democratic Party forum this coming weekend, in fact.) In RealClearPolitics’ aggregation of national polling, Biden’s bounced back this summer to track above 30% while no one else tracks above 20%.

Meanwhile, Harris’ polling has been crumbling since she peaked after the first debate. She’s now fallen below 10% in her RCP average and is about to drop into the second tier, barely polling above Pete Buttigieg:

Harris can’t afford to allow that decline to continue all the way to the official DNC debate in late September. She needs a game-changer, and it’s a sure bet that her flip-flop on Medicare for All isn’t going to help. So why won’t Harris make room to participate in a “climate crisis” town hall, where all that’s expected is bromides about how Donald Trump is killing the planet and each candidate will pledge not to be a Trump?

The answer might be in the curve above. Harris made the leap out of the second tier by using the first debate in late June to attack Joe Biden over busing, who was clearly unprepared for combat. In the days that followed, Harris blew the opportunity by shifting her own position on busing until it began looking suspiciously similar to Biden’s. In contrast to the strategic surprise Harris had in the first debate, Tulsi Gabbard had been attacking Harris over her sandbagging of Biden as a racist since the end of the first debate, and yet somehow Harris was completely taken off guard when Gabbard attacked in the second debate. Her decline began in earnest from that point and has accelerated since.

Harris has no choice but to attend the DNC debates. Dodging this one makes it look pretty clear that her team doesn’t have much confidence in her ability to handle even mildly hostile environments and sharp engagement in live television. If that’s the case, why is Harris running for president at all?

Addendum: CNN’s decision not to highlight Harris’ demurral is understandable because they have an interest in promoting their program. We’ll see if other news outlets focus more on Harris’ answer.