A Republican state lawmaker in Nebraska on Monday said members of his party enable white supremacy in the U.S. by staying silent when President Donald Trump “stokes racist fears in his base.”

State Sen. John McCollister said in a series of tweets that he doesn’t believe all Republicans are white supremacists or racists, but that his party is “complicit to obvious racist and immoral activity in our party.”

“We have a Republican president who continually stokes racist fears in his base,” McCollister wrote. “He calls certain countries ‘sh*tholes,’ tells women of color to ‘go back’ to where they came from and lies more than he tells the truth.”

“When the history books are written, I refuse to be someone who said nothing,” he added.