A liberal Massachusetts blog has published video of men identified as staffers for Sen. Scott Brown (R-Mass.) chanting "war whoops" and making "tomahawk chops" during a rally.

Local news station WCVB confirmed that the men seen in the video are Brown's deputy Chief of Staff Greg Casey and Constituent Service Counsel Jack Richard, along with Brad Garrett, a local Republican activist. The Washington Post has not independently confirmed their identities. 

Native American heritage has become a flashpoint in the tight race between Brown and Harvard Law professor Elizabeth Warren (D). 

Brown has repeatedly attacked Warren for telling past employers that she has Native American heritage. His opening statement in last week's debate focused on the controversy, as does his most recent ad. 

Warren says she never received any professional advantage from identifying as part Cherokee. Brown has demanded she release personnel records to substantiate that claim. 

According to Blue Mass Group, the blog that posted the clip, the rally took place in Boston on Saturday. Warren supporters holding signs also appear in the video. 

Brown's campaign did not immediately respond to a request for comment. Brown told WCVB that the behavior is "something I don't condone." But, he said, "The real offense is that [Warren] said she was white and then checked the box saying she is Native American, and then she changed her profile in the law directory once she made her tenure."