(CNN) A Republican state representative is speaking out against what he believes is his own party's complicity in "enabling white supremacy," and says history won't judge his fellow Republicans kindly.

Nebraska state legislator Rep. John McCollister tweeted Sunday night, "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."

The Twitter thread came one day after a white supremacist killed at least 20 people in El Paso, Texas . The criticism came as some politicians began pointing to the rhetoric from the Republican Party and the current administration as a contributing factor for the violence.

McCollister, who represents part of Omaha, said that he didn't think all Republicans are racist or white supremacists, but "the Republican Party is COMPLICIT to obvious racist and immoral activity inside our party."

"We have a Republican president who continually stokes racist fears in his base. 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," he added.