Sen. David Perdue said he backs President Donald Trump’s threat to release immigrants apprehended at the U.S. border into “sanctuary cities” in Democratic strongholds.

Perdue said Monday that Trump’s comments were aimed at spurring Congressional action to stem “an explosion at the borders and exploding illegal drug traffic” at the border with Mexico.

“I don’t understand why the cities are trying to stand against the federal law,” he said of local governments that adopted sanctuary policies. “What the president is saying is right - there is an absolute five-alarm crisis at the border. It’s not just human trafficking, it’s drug trafficking.”

Perdue’s remarks came after he gave a speech at a tea party rally in Atlanta as he prepares to run for another term in 2020. The Republican has long positioned himself as one of Trump’s most loyal allies, a stance Democrats hope to turn into a weakness.

Georgia law has long prohibited cities and counties from adopting a sanctuary policy, but some local leaders have announced decisions to limit cooperation with federal authorities and embraced “welcoming” policies.

Atlanta Mayor Keisha Lance Bottoms has championed that approach. She signed an executive order last year barring the city jail from holding U.S. Immigration and Customs Enforcement detainees – earning a rebuke from Vice President Mike Pence.

And over the weekend, she used exceedingly harsh terms to condemn Trump’s idea.

"To turn the clock back to an era when certain segments of society were treated as property is immoral," she wrote on Twitter. "This fearmongering is feeding the rise of hate crimes in our country and is nothing more than a xenophobic game of partisan politics. We are better than this."

In the interview, Perdue was asked if he still supports the policy if those detained immigrants were moved to Atlanta. He shifted his criticism to cities that ignore federal immigration policies, and brought up an undocumented immigrant who was charged - and acquitted - in the death of Kate Steinle in 2015.

“That’s the unconscionable thing that happens when these people think they’re doing the liberal thing – good people suffer for that,” Perdue said. “And that’s what I think most people want to end.”