A Republican candidate for a U.S. Senate seat in Arkansas says he sees no need to apologize for comparing stem cell research to Nazi experiments on Jews during the Holocaust.

Curtis Coleman told nationally syndicated radio host Thom Hartmann on Thursday that he stood by his statement that embryonic stem cell research was similar to “what the Nazis did to the Jews.”

Coleman is one of eight Republicans running for the chance to challenge Democratic Sen. Blanche Lincoln.

Coleman is the chief executive officer of Safe Foods Corp. in North Little Rock and managed former Gov. Mike Huckabee’s unsuccessful 1992 Senate bid. He made the stem cell comment during an interview with a Little Rock television station earlier this week.