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The mass shooting at a Walmart in El Paso, Texas, last August that left 22 dead was "the worst carnage wrought by domestic extremists" last year, according to a report released Wednesday that found an increase in the number of white nationalist groups in the United States for the second straight year.

The report by Southern Poverty Law Center reported, which tracks white nationalism, white supremacy and hate groups, identified 155 white nationalist groups in the U.S. last year, up from 148 in 2018 and a 55 percent increase since 2017.

Authorities say the gunman in the Aug. 3 attack in El Paso told police that his target was "Mexicans" and that he posted a manifesto before the attack that included anti-Latino and anti-immigrant rhetoric. The SPLC has reported that the gunman's screed contained white nationalist talking points "on “ethnic displacement" and "race mixing" and refers to immigrants to the United States as "invaders."

Radical right's fear of "white genocide"

According to the report, "the most powerful force animating today’s radical right—and stoking the violent backlash—is a deep fear of demographic change," and the idea that "white genocide" is under way.

The SPLC said there is a growing threat from a sector of white supremacists who call themselves “accelerationists” who believe violence is the tool that can counter increasingly pluralistic, democratic governments.

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That ideology is believed to have been followed by the gunman in the attacks on two mosques in Christchurch, New Zealand, on March 15, 2019. The SPLC said white nationalism violence is also rising globally.

Amid the increase in white nationalist groups, there was a dip in hate groups from 1,020 to 940 last year, largely due to a collapse in Neo Nazi groups and a decline in Ku Klux Klan, Christian identity and neo-Confederate groups, SPLC senior researcher Howard Graves told NBC News.

But the SPLC writes that the decline of those groups has been replaced with a broader acceptance of white nationalist ideas under President Donald Trump's administration.

The SPLC last year released hundreds of emails of Stephen Miller,the architect of Trump’s immigration policies such as the child-parent separations at the border and the Muslim ban, in which he cited and promoted "explicitly white nationalist websites."

“As the country continues to experience white nationalist terror, extremist ideas long believed outside of the realm of legitimate politics are penetrating deeply into the mainstream, spawning public policies that target immigrants, LGBTQ people and Muslims,” the SPLC said in its report.

“Inclusive democracy is in the crosshairs of hate and bigotry. White nationalists no longer seek to simply spread their views — they are committed to seizing the power of the state,” Eric Ward, executive director of Western States Center, a social justice organization that advocates for “inclusive democracy,” said in a statement.

Sharp rise in anti-LGBTQ groups

The SPLC has also logged a sharp expansion of anti-LGBTQ groups, up 43 percent from 49 in 2018 to 70 last year and a smaller increase in anti-immigrant groups from 17 in 2018 to 20 last year.

The FBI found last year that nearly 1 in 5 crimes were motivated by anti-LGBTQ bias.

“The resurgence of these groups poses a real danger to LGBTQ people and to the progress we have made, which feels increasingly precarious in the face of this administration’s shocking support for anti-LGBTQ groups and apparent determination to roll back even the most basic legal protections for LGBTQ people,” said Shannon Minter, legal director of the National Center for Lesbian Rights, who was part of a teleconference on the SPLC report.

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