House Democrats grilled officials from the FBI and Department of Homeland Security in a Tuesday hearing focused on how the Trump administration is addressing the growing threat of violent white supremacist extremists.

The House Oversight subcommittee on civil rights and civil liberties hearing, titled 'Confronting White Supremacy: Adequacy of the Federal Response,' was the latest effort by Democrats to spotlight ways they say the Trump administration has systematically cut back on resources used to address threats from domestic extremists even as the FBI has reported a 30-40% rise in domestic terrorism cases just since October.

Federal officials in attendance at Tuesday's hearing included FBI Assistant Director for Counterterrorism Michael McGarrity, FBI Deputy Assistant Director for Criminal Investigations Calvin Shivers and DHS Assistant Secretary Elizabeth Neumann.

Committee chairman Rep. Jamie Raskin, D-Md., opened the hearing by raising issue with the amount of resources he says the FBI devotes towards investigating cases of international terrorism versus domestic terrorism.

Citing figures from the Anti-Defamation League, Raskin noted that from 2009-2018, far-right extremism was responsible for 73% of extremist murders, while international terrorism was responsible for 23% of terrorism deaths.

"The FBI has testified the bureau allocates its resources almost exactly backwards than the problem would suggest," Raskin said. "Devoting 80% of field agents to stopping international terrorism including Islamic extremism and only 20% to stopping domestic terrorism including far right and white supremacist extremism."

But McGarrity pointed to the success that FBI agents have so far had in disrupting potential domestic attacks in the past several months, and said successful arrests prior to domestic attacks actually outnumbered those arrested prior to attacks in international terror cases.

"In fiscal year 2018 FBI (Joint Terrorism Task Forces) across the country proactively arrested approximately 115 subjects of FBI domestic terrorism investigations before they could mobilize into violence," McGarrity said. "So far (since Oct. 1 of last year), our JTTFs have disrupted approximately 66 subjects of FBI domestic terrorism investigations by arrest."

Rep. Debbie Wasserman-Schultz, D-Fla., pressed Neumann on a report that the department recently disbanded and slashed funding for a section of the Office of Intelligence and Analysis, which focused on producing reports on domestic terrorism and which Democrats warn could result in a reduction of available data on threats from white supremacist groups.

Neumann countered that the funding dedicated to the department was only inflated due to millions in grant funding committed during the Obama administration, but later in the hearing gave a candid assessment regarding DHS' overall counterterrorism strategy, saying that the administration is actively working to find ways to improve its prevention strategy.

"We know we're not doing enough," Neumann said. "Things haven't been institutionalized. In order for government to work, we have to institutionalize it, you either need to authorize it through Congress or you need to get it in executive order or national security presidential memoranda."

Following the terror attack on several mosques in New Zealand in March carried out by an alleged white supremacist, President Donald Trump told reporters he didn't see white nationalism as a rising threat to the U.S.

The hearing followed a briefing just two weeks earlier from a senior FBI counterterrorism official who gave sobering statistics to reporters regarding the domestic threat environment.

The official revealed the FBI currently has a total of just under 5,000 open terrorism cases, including 850 domestic terror-related cases, and acknowledged that far more Americans have been killed in domestic terror attacks than Islamic terror attacks since the Sept. 11, 2001 attacks.

According to the official, a significant issue that the bureau faces is that the federal criminal code has made it more challenging to bring charges against domestic terror suspects than in cases involving international terrorism or foreign terrorist organizations.

That's because, according to the FBI Agents Association, "domestic terrorism" itself is not a federal crime.

"Domestic terrorism is about political violence," Tom O'Connor, the president of the FBI Agents Association said in a statement to ABC News. "Congress must do everything in its power to provide law enforcement with the tools needed to combat this threat to our country."

Investigators often are forced to rely on other federal crimes to charge suspects with or rely on state or local laws, such as in the recent case of Coast Guard Lt. Christopher Hasson, who despite being accused in court of plotting mass murder "on a scale rarely seen in this country," is currently facing only gun and drug charges from U.S. attorneys in Maryland.

And while then-Attorney General Jeff Sessions initially described the Charlottesville, Virginia attack by James Fields Jr., which resulted in the death of Heather Heyer, as "the definition of domestic terrorism," Fields in March pleaded guilty to 29 counts of violating federal hate crime law.

The issue surfaced in a contentious exchange between Rep. Alexandria Ocasio-Cortez, D-N.Y., and McGarrity, where McGarrity was pressed on why the 2015 Emanuel AME Church shooting in Charleston, South Carolina, and last year's Tree of Life Synagogue shooting in Pittsburgh were treated as "hate crime incidents" rather than acts of domestic terrorism.

"That's not correct," McGarrity said, pointing out that while the attacks are considered instances of domestic terrorism by the Department of Justice, "there's no domestic terrorism charge."

In an emotional exchange on the subject later in the hearing, Rep. Rashida Tlaib, D-MI, read a death threat letter sent to her and fellow Muslim congresswoman Rep. Ilhan Omar that cited the New Zealand mosque attacks and remarked, "the only good Muslim is a dead one."

"How is that not enough to fall under domestic terrorism?" Tlaib said through tears. "How come we don't have enough tools right now to pull these people in?"

McGarrity expressed sympathy for Tlaib and urged her to bring her concerns directly to the Department of Justice, after earlier noting he personally would welcome Congress passing a law that makes domestic terrorism a federal crime.

“I will say as a former prosecutor and as a former investigator, I want every tool in the tool box,” McGarrity said.