Already, the DNC rules have thinned the field of candidates who will appear onstage in Houston for the third televised debate Sept. 12 and potentially the next night as well. Only 10 candidates have qualified so far, with possibly two or three more getting in ahead of the Aug. 28 deadline.

The field of eligible candidates may actually grow bigger for the October debate, since the DNC has decided not to raise the polling threshold above 2 percent from its September rules and will also keep the marker for small-dollar donations at 130,000.

But in November the DNC, which is increasingly under fire for its handling of presidential debates, is likely to raise the polling requirement above 2 percent, according to multiple sources involved in the process who spoke to Yahoo News about internal deliberations on the condition they not be identified.