Joe Biden blasted President Donald Trump in a speech in Iowa on Wednesday for instigating racial violence and hate crimes in the United States through his anti-immigrant and white supremacist rhetoric.

The former vice president delivered his comments before supporters in Burlington, Iowa. Biden’s remarks follow two unrelated mass shootings that took place in El Paso, Texas and Dayton, Ohio over the weekend, where 22 and nine people were killed, respectively. Dozens more were injured in the massacres.

“We have a problem with this rising tide of white supremacy in America and we have a president who encourages it and emboldens it,” Biden, the 2020 Democratic presidential frontrunner, told the crowd. “Indeed, we have a president with a toxic tongue who has publicly and unapologetically embraced the political strategy of hate, racism and division.”

Biden also said he believes Trump has unleashed the “deepest, darkest forces in this nation.”

Patrick Crusius, the 21-year-old extremist perpetrator behind the El Paso attack, shared online a white nationalist manifesto that voiced fear of a “Hispanic invasion of Texas.”

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Biden also compared Trump to late segregationist Alabama Gov. George Wallace and emphasized he believes the 2020 election will be a “battle for the soul of this nation.”

Trump responded to Biden on Twitter on Wednesday as he traveled from Dayton to El Paso, using the moniker “Sleepy Joe” to mock the former vice president and criticize the “LameStream media” for covering him.

Biden also cited examples in his speech on Wednesday of former presidents from both parties who stood up for American values and whose words and actions after domestic terror attacks he believes were more positively impactful than Trump’s.

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“George H.W. Bush renouncing his membership in the NRA. President [Bill] Clinton after Oklahoma City. George W. Bush going to a mosque after 9/11. President [Barack] Obama after Charleston. Presidents who led chose to fight for the best of what American character is about,” Biden said. “There is deafening silence now … our president has aligned himself with the darkest forces and it makes winning the battle for the soul of our nation that much tougher.”

Since taking office, Trump has referred to large groups of illegal Hispanic migrants approaching the southern border in a caravan as an “invasion” during rallies and other events. Trump’s critics have blamed the president for the mass shooting in El Paso after noting that the perpetrator cited Trump directly in it.

In his White House address on Monday responding to the shooting, Trump denounced all forms of hatred and racism, including white nationalism. However, he appeared to blame violent video games and mental illness more for these types of tragedies.