Update at 3:30 p.m. ET, Sept. 27

Alleigh Marre, a spokeswoman for Massachusetts Sen. Scott Brown's campaign, released a statement, saying:

"Senator Brown has spoken to his entire staff – including the individuals involved in this unacceptable behavior – and issued them their one and only warning that this type of conduct will not be tolerated. As we enter the final stretch of this campaign, emotions are running high, and while Senator Brown can't control everyone, he is encouraging both sides to act with respect. He regrets that members of his staff did not live up to the high standards that the people of Massachusetts expect and deserve."

-- Original story below --

The principal chief of the Cherokee Nation is calling on Sen. Scott Brown, R-Mass., to apologize for a video that allegedly shows members of his staff imitating "stereotypical 'war whoops chants.'"

As WBUR's Curt Nickisch reported Tuesday for All Things Considered, Brown's supporters werefilmedimitating "tomahawk chops" at a rally in Dorchester, Mass., over the weekend. The antics were apparently directed at Elizabeth Warren, Brown's Democratic opponent in the Senate race; Warren has been criticized for telling previous academic employersthat she has Native American heritage.

Now, Brown and the GOP are under fire for supporters' actions that "goes far beyond what is appropriate and proper in political discourse," Cherokee Chief Bill John Baker said in a statement Wednesday.

"The use of stereotypical 'war whoop chants' and 'tomahawk chops' are offensive and downright racist," he said. "It is those types of actions that perpetuate negative stereotypes and continue to minimize and degrade all native peoples."

Early Tuesday, Brown said he didn't condone the action at the rally.

The Boston Globe has reported that two of the people in the video were Republican staffers, "including a member of Scott Brown's U.S. Senate office."

The New York Times reports that Warren called the video "appalling." A second video originally posted by the Chatham Republicans and reposted by the Blue Mass Group on Wednesday shows Brown speaking at a rally this summer about Warren's heritage as "war whoops" can be heard.

Baker said Brown's comments Tuesday didn't go far enough, and called for a full apology:

"We need individuals in the United States Senate who respect Native Americans and have an understanding of tribal issues. For that reason, I call upon Sen. Brown to apologize for the offensive actions of his staff and their uneducated, unenlightened and racist portrayal of native peoples."

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