Public Policy Polling (PPP) is out with its latest national survey on the Democratic contenders for president. Most news reports will no doubt focus on the fact that Hillary Clinton leads Bernie Sanders 35 percent to 28 percent. PPP also polled for Joe Biden, with the sitting veep grabbing 20 percent of voters questioned.

But PPP, which is usually billed as a left-leaning pollster, didn’t stop there. It polled for Jim Webb, Lincoln Chafee and Martin O’Malley — who got 2 percent, 1 percent and 1 percent, respectively — and it also tested what it called a “fantasy field” including “all of the names that have been thrown out there as possible Clinton challengers.”

In that free-for-all, Clinton tops out with 37 percent, with Biden grabbing 20 percent, Sanders 19 percent, 11 percent for Elizabeth Warren, 4 percent for Al Gore and 2 percent each for Michael Dukakis and John Kerry. Martin O’Malley still brings up the rear at 1 percent.

But there’s a problem with that sampler plate, and it’s not just that some of the offerings have long gone cold.

Lawrence Lessig, a Harvard Law professor and Net neutrality advocate, is an actual, announced candidate for president of the United States. “Larry” — as his campaign materials call him — has raised $1 million in the last month from about 10,000 donors. Lessig was also included in the last PPP survey [PDF], taken just over a month ago, and received 1 percent — equal to Chafee’s total at the time.

But Lessig’s omission from the PPP poll this time is more than just academic for the academic. According to CNN, the host of the first Democratic presidential debate next week, a candidate must log at least 1 percent in three national polls in the six weeks prior to the debate in order to make the cut and be allowed on stage. CNN even went so far as to tell Biden that he’d be welcome to join in — even if he waited until the day of the debate to declare his candidacy — because he is polling fairly well in a number of national opinion surveys.

But if Lessig isn’t even being included in the polls, even by organizations that had offered up his name five weeks prior, how is he supposed to meet the television network’s requirement? And if he isn’t on TV, how is he to raise his visibility for the pollsters?

It isn’t so much a Catch-22 as the result of arbitrary calls by television programmers. And it is hardly a first.

CNN has already hosted a GOP debate. That event, the second in that string, featured 11 candidates on stage — a tricky number to square, as until about a week before, CNN said its criteria was set to include the top 10 candidates in an assortment of national polls.

But 10 was a number that would have left out someone. Now, picking 11 has left out someone, too. Four someones, to be exact. But CNN had decided 11 made the most sense.

The first two Republican debates have been ratings juggernauts, and CNN likely didn’t want to disappoint its huge audience. A stage with only 10 participants would have left out someone from the bottom tier that network folks might have thought would make for some good viewing (and maybe some good viral video afterwards) — someone like Chris Christie, for instance.

Fox, the host of the first GOP debate, took only 10 for its prime-time tussle, but even then, the criteria for how those 10 were picked (specifically how Fox chose the polls it counted) shifted in the days right before the big event.

If this were just about ratings, none of this would much matter, except to the network execs and ad sales departments at the cable news channels. But there is substantively more at stake than just the cost-per-minute to advertisers.

The influence of televised debates remains a matter of debate. Research seems to show that in changing opinions when the choice is between only two candidates, the effect is minimal. But their impact can be much greater early in the race, when these debates are as much about visibility, poll numbers and fundraising — and thus about winnowing the field — as they are about winning individual votes.

That means the decision-makers at CNN and Fox, and the networks that will follow this primary season, are playing a surprisingly important roll in helping choose the next president — and not just through the free dissemination of vital information.

Pollsters, too, as PPP has explicitly proven this month, are also now more involved than should make them comfortable. (In fact, one polling firm was so uncomfortable with having its data used this way that it specifically avoided the presidential preference question in a survey before the first GOP debate).

One would think there is a way around this. The national political parties, the Democratic National Committee and Republican National Committee, which for the most part control their presidential primaries, could theoretically take command of the debate selection process, too. In fact, it appeared the RNC was about to do that, stating a couple of weeks ago that the third of their presidential debates would not limit the number of canddidates on the main stage, and would eliminate the “kids’ table” second debate. But, as the campaigns have ebbed and flowed and the leaderboard has shifted, it seems the Republican Party will again defer to television producers who want a hand in the casting.

The Democratic debate next Tuesday, however, is not expected to be as big a ratings windfall for CNN as the GOP show was, giving the network the opportunity to make a different choice. Many would see adding Lessig to the dais as a decision to reduce the role of TV producers and pollsters in shaping election news.