When ultra-conservative Jesse Helms ran against Congressman Nick Galifianakis in 1972, he is considered to have gained ground with the slogan, "Jesse Helms: He's One of Us," presumably referring to his opponent's Greek background. If his opponent were black, the slogan would be considered racist. What's the corresponding word for this situation? Ethnicist seems too mild but may be best.
The correct term is still racist. The definition of race includes ethnicity: