See an interesting example below the letter.
Letter Southern Poverty Law Center https://www.cotton.senate.gov/files/documents/2019%20SPLC%20Cotton%20Letter%20VF.pdf
Excerpt from “Once Again We Were Attacked by The SPLC“, FEBRUARY 9, 2020 BY KEVIN LYNN “The funny thing is the last time they attacked us and devoted a page on their website to PFIR [Progressives for Immigration Reform] and our programs, they insinuated our then and long-serving Executive Director, Leah Durant, was a racist. After taking a little bit of time to bask in the SPLC’s attention, Ms. Durant sent them an email informing them she was a black American and had over the course of her life experienced real racism as opposed to the synthetic kind conjured up by the SPLC and its minions. Although they did not issue an apology, they did pull from their website all references to PFIR…
As the son of an immigrant, I always found it peculiar that the SPLC would view my organization as anti-immigrant. But anyone looking to restrict immigration so that it works in the interests of the citizens is, in the plank-filled eyes of the SPLC, anti-immigrant…” See: https://www.ustechworkers.com/splc-attacks-group-standing-up-for-working-men-and-women and https://progressivesforimmigrationreform.org