There are other examples — enough, in fact, that a relatively unknown candidate at 1 percent of the vote could be thought to have a better chance at winning than a well-known candidate at 10 percent, like a Jeb Bush in 201 5.

In general, early polls do a decent job of identifying the candidates likeliest to win the nomination. To take a simple example: Most candidates with steady and significant polling leads over the first six months in the year before the election go on to win the nomination. There are many exceptions, but it would be wrong to say the early polls are “meaningless.”

But this is a subtly different and easier task than deciding who should make the first debates and who should not. It’s one thing to know that a candidate who’s strong in the polls should be taken seriously; it’s something else entirely to know that one who is weak in the polls shouldn’t be taken seriously.

Many strong candidates weren’t even in the race at this stage, including the current president of the United States (he announced June 16 in 2015). Donald J. Trump would have qualified for the debate — he was included in several polls before he entered the race, and his celebrity was good for a couple of points in a few polls. He averaged 2 percent in the early polls conducted before he entered the race.

Mr. Bullock, though, is no celebrity. He starts with low name recognition, so unlike a well-known candidate with 1 or 2 percent support, he can hope that he’ll break out when given a moment in the spotlight.

He has some reasonable excuses for not having more name recognition.

He was the second-to-last candidate to enter the race (two days before Mayor Bill de Blasio of New York), so his failure to break out by the debate deadline might not necessarily reflect weakness as a candidate. He has not had a CNN town hall event, which several candidates have used to propel themselves higher in the polls. In fact, Mr. Bullock entered the race so late that many pollsters did not include him in qualifying polls, and he was also at a disadvantage in meeting the alternative debate entry criteria of fund-raising.

He also hails from Montana, one of the least populous states in the country — a subtle but real disadvantage in the fight for 1 percent of the vote in the polls.