The Nebraska Republican Party asked a lawmaker to leave the party on Monday after he accused the party of "enabling white supremacy."

State Sen. John McCollister, who has represented part of Omaha since 2014, criticized his party in a series of tweets on Sunday, saying that the GOP had become "complicit to obvious racist and immoral activity inside our party."

Following two mass shootings in El Paso, Texas, and Dayton, Ohio, that left 31 people dead, McCollister wrote on Twitter, "The Republican Party is enabling white supremacy in our country. As a lifelong Republican, it pains me to say this, but it’s the truth."

McCollister continued his rant, taking aim at President Donald Trump.

"We have a Republican president who continually stokes racist fears in his base," McCollister explained. "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," he said. "I refuse to be someone who said nothing."

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The El Paso shooter published a "manifesto" filled with racist and anti-immigrant rhetoric before his rampage, and authorities said they would be investigating the killings as a hate crime.

By Monday, the state Republican Party responded to McCollister.

In a press release, party Chairman Ryan Hamilton said McCollister had "finally shed all pretense of being a conservative."

"I am happy to send a change of voter registration form along to his office so he can make the switch officially and start, for once, telling the truth to voters in his district," said Hamilton.

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McCollister showed no signs of backing down, though.

Appearing on CNN later Monday, he said, "We've seen the Republican Party leave its moorings. The Republican Party of today is hardly anything like the party I knew when I was growing up."

He added that he was "disappointed in Republican officeholders for allowing President Trump to say some of the hateful things that he's said, and It's time for them to stand up for a change and make it known that they don't condone that kind of hateful speech."