One of the more common defenses of the Redskins name is that it's only a small proportion of American Indians calling for the change. Short of getting the five or so million natives left on a conference call, I'm not sure how you counter that argument. But this seems worth a shot.
The National Congress of American Indians, which counts among its membership hundreds of tribes from all over the country*, has released this video featuring seven elected tribal leaders, two of them national officials, speaking out against Washington's use of "Redskins" as a team name.
And unlike Dan Snyder's chosen pitchman, presumably these seven have had their credentials checked.
* We'd originally said the NCAI includes every federally recognized tribe among its voting membership. Sentence is fixed now.