The mainstream media will report the Democrat debate from Las Vegas, Nevada, on Wednesday evening as the latest event in the primary calendar. But it is an event over which they exert significant control — and not just through their coverage.

The Democratic National Committee (DNC) debate rules specify that only those candidates who reach certain key thresholds in national polls or early-state polls in a limited timeframe can qualify for the debate stage.

The catch: the only polls recognized by the DNC are those conducted by certain established media outlets and academic pollsters. And there is no requirement that any of those outlets actually conduct any polls in a particular timeframe.

Billionaire left-wing donor Tom Steyer found that out the hard way this week, when he failed to qualify for the debate stage in Las Vegas even though he had met the minimum 10% polling threshold in four polls in Nevada and South Carolina. None of the polls that showed him doing well in those states was considered a qualifying poll by the DNC.

Worse, the DNC criteria for the Nevada debate used a shortened timeframe that excluded earlier polls in those states. And as Steyer noted, there were no polls conducted by DNC-approved outlets in Nevada and South Carolina within the timeframe, meaning that there was no way Steyer could have qualified for the debate except through nationwide polls.

While the DNC was willing to change its rules — eliminating the requirement of a minimum number of donors — in a way that allowed Mike Bloomberg to make the stage, it rejected a request by Steyer to extend the polling window.

Steer may not exactly be a sympathetic figure; the DNC thwarted his tactic of juicing state polls by spending big on local media markets.

But what his exclusion points to is the fact that the mainstream media and the academy have outsized influence in selecting the candidates on the debate stage.

If the DNC-approved organizations had wanted to ensure a fair playing field, they could have polled Nevada and South Carolina. The fact is that they chose not to do so.

Joel B. Pollak is Senior Editor-at-Large at Breitbart News. He earned an A.B. in Social Studies and Environmental Science and Public Policy from Harvard College, and a J.D. from Harvard Law School. He is a winner of the 2018 Robert Novak Journalism Alumni Fellowship. He is also the co-author of How Trump Won: The Inside Story of a Revolution, which is available from Regnery. Follow him on Twitter at @joelpollak.