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WASHINGTON, DC - APRIL 26: Sen. John McCain (R-AZ) speaks at a press conference to show support of professional fighters study at Cleveland Clinic Lou Ruvo Center for Brain Health on April 26, 2016 in the Russell Senate Building in Washington, DC. (Photo by Paul Morigi/Getty Images for Spike TV)

WASHINGTON, DC - APRIL 26:  Sen. John McCain (R-AZ) speaks at a press conference to show support of  professional fighters study at Cleveland Clinic Lou Ruvo Center for Brain Health on April 26, 2016 in the Russell Senate Building in Washington, DC.  (Photo by Paul Morigi/Getty Images for Spike TV)