President Donald Trump's nominee to lead the agency in charge of curbing domestic terrorism told senators that White supremacists have become the "most persistent and lethal threat" to the U.S. from within the country.

"White supremacist extremists, from a lethality standpoint over the last two years, particularly when you look at 2018 and 2019, are certainly the most persistent and lethal threat when we talk about domestic violent extremists," said Chad Wolf, who has been heading the Department of Homeland Security in an acting capacity since late last year.

The response is notable considering that Trump and Attorney General William Barr have sought to portray the nation as besieged by "left-wing" agitators fomenting violence in protests over racial injustice.