He said leaders of "sanctuary cities" should be federally prosecuted for harboring lawbreakers, defining a sanctuary city as any jurisdiction that does not require authorities to actively check the immigration status of people in police custody.
"Our immigration policy should put American workers first, the citizens who make this country run, who go to work, pay their taxes and follow the law," said Stewart, who has chaired the Prince William Board of County Supervisors since 2006.
Throughout his political career, Stewart has repeatedly turned to resentment in Virginia over illegal immigration as a way to rally conservative voters, often telling supporters that he was "Trump before Trump was Trump."
On Thursday, he cited a 2005 case where a deaf and mute Salvadoran national was accused of raping and killing Brittany Binger, 16, in Williamsburg, and a 2010 case where Denise Mosier, 66, a Catholic nun in Prince William, was killed in a car accident caused by a Bolivian man who was scheduled to be deported and had been convicted of driving drunk.
"I have compassion for Sister Mosier and all the victims of crimes committed by illegal aliens," Stewart said.
When launching his Senate bid last year, Stewart promised to run a "vicious, ruthless campaign" that would go beyond the one he ran against Gillespie, where he whipped up white-nationalist anger by focusing largely on preserving Virginia's Civil War heritage.
He faces competition in the Republican primary from state Del. Nicholas J. "Nick" Freitas (Culpeper), Army veteran Ivan Raiklin and E.W. Jackson, a fiery preacher whose views on immigration are similar to Stewart's.
Stewart said he is not worried about the competition.
"I'm the only one out there, of all the candidates running, who has got name ID and a brand," he said. "This primary is going to be: Either you're voting for Corey Stewart, or you're voting against Corey Stewart."