He said Republican lawmakers look the other way and say nothing because they are afraid of losing elections.

“No more,” he wrote. “When the history books are written, I refuse to be someone who said nothing. The time is now for us Republicans to be honest with what is happening inside our party. We are better than this and I implore my Republican colleagues to stand up and do the right thing.”

Nebraska’s Republican Gov. Pete Ricketts appeared to respond to McCollister on Monday afternoon with his own series of tweets, although he did not refer to the legislator by name.

“White supremacy and racism have no place in our country, and they must be driven out. I have said this repeatedly and will say it again and again,” Ricketts tweeted. “Contrary to baseless accusations made on social media, the Republican Party does not tolerate such hateful views.”

The executive director of the Nebraska Republican Party, Ryan Hamilton, responded to McCollister by issuing a statement via Twitter suggesting that the state senator re-register as a Democrat.

Hamilton said McCollister has opposed conservative policy positions on issues ranging from taxes to abortion.