A former FBI counterterrorism agent, Dave Gomez, told The Washington Post he thought that a fear of being seen as targeting President Donald Trump's base was muting the agency's response to violence by white nationalists.

"There's some reluctance among agents to bring forth an investigation that targets what the president perceives as his base," Gomez told the publication.

The comments followed an attack on Saturday by a gunman at a Walmart in El Paso, Texas, that the FBI is treating as a domestic terrorism incident.

Investigators have said the gunman left a racist manifesto on the messaging board 8chan ahead of the attack.

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FBI agents are hesitant to investigate white nationalist extremists because they don't want to be seen as pursuing investigations against President Donald Trump's base, a former FBI counterterrorism agent told The Washington Post.

The former agent, Dave Gomez, said he believes that FBI Director Christopher Wray "is an honorable man, but I think in many ways the FBI is hamstrung in trying to investigate the white supremacist movement like the old FBI would."

"There's some reluctance among agents to bring forth an investigation that targets what the president perceives as his base," Gomez said. "It's a no-win situation for the FBI agent or supervisor."

He said that Trump's repeated criticism of the FBI and its investigation into Russian election interference and collusion were likely factors as well.

The FBI declined to comment to Business Insider on Gomez's claims. An FBI representative told The Post that the comments were not accurate and that the agency distributes resources according to its assessment of the threat posed by domestic terrorism.

FBI Director Christopher Wray. Evan Vucci/AP

According to The Wall Street Journal, the FBI says about 40% of the domestic terrorism cases it is investigating involve racism.

Gomez's comments followed Saturday's shooting in a Walmart in El Paso, Texas, that killed 20 people. Investigators have told media outlets that shortly before the shooting, the gunman posted a racist and anti-immigrant screed on the messaging board 8chan, known as a hub for white nationalists. Authorities have identified Patrick Crusius as the suspect in the shooting.

That shooting was followed hours later by another mass shooting in Dayton, Ohio, that investigators have not tied to racist ideology. Authorities have not publicly identified a motive in that shooting.

Saturday's shooting was the latest in a long series of deadly attacks by white nationalist extremists in the US and abroad. In March, a gunman killed 51 people in mosques in Christchurch, New Zealand, and livestreamed the attack on social media.

At a Senate hearing in July, Wray said an increasing number of domestic terrorism incidents were motivated by white supremacist and white nationalist ideologies.

Law-enforcement responses to violence by white nationalists have long been the focus of fierce bipartisan disputes. Republicans in 2009 reacted furiously to a Department of Homeland Security report that described right-wing extremist violence as a rising threat. They accused the agency of a bid to smear conservatives.

Trump's political opponents have accused him of deliberately stoking racist divisions in the US and actively courting the support of white nationalists during his 2016 presidential campaign.

In a March op-ed article for Time, the director of the Center for the Study of Hate and Extremism at California State University linked a rise in white nationalism to "a coarsening of mainstream politics, where debates on national security and immigration have become rabbit holes for the exploitation of fear and bigotry."

The president last week claimed he is "the least racist person anywhere in the world" and on Sunday linked the El Paso attack to a "mental-illness problem." In the wake of the New Zealand attack, he said he didn't see white nationalism as a growing global threat.

Under US law, while it is a crime to provide support for foreign terror groups like ISIS, there is no equivalent for domestic terrorism organizations, The Post said.

The FBI is investigating the El Paso attack as a domestic terrorism incident and possible hate crime. In a statement on Sunday, it warned that Saturday's attack could inspire copycats.