President Donald Trump slammed Illinois Gov. JB Pritzker during a press conference in Alberta, Canada, today, labeling the Illinois official one of "the worst in the country."

This remark followed Pritzker's defense of his state's sanctuary laws in front of a Congressional committee late last week.

Here's what happened.

Trump calls Pritzker 'worst in the country'

While discussing sanctuary cities during a June 16 press conference, Trump brought up New York City and Chicago, criticizing the Illinois city's mayor and governor, according to a clip published online by Fox News.

"I look at New York, I look at Chicago," Trump said. "I mean, you've got a really bad governor in Chicago and a bad mayor. But the governor is probably the worst in the country – Pritzker."

He then went on to claim that Chicago has been "overrun by criminals."

Pritzker defends sanctuary laws before Congress

Pritzker defended Illinois' sanctuary laws for undocumented immigrants at a hearing before Congress on June 12, alongside Minnesota Gov. Tim Walz and New York Gov. Kathy Hochul.

During the hearing, held before the House Oversight and Government Reform Committee, Pritzker accused Trump of what he called "abuses of power," referencing the administration's deployment of the military to Los Angeles in response to ongoing protests , according to ABC News.

"Illinois follows the law, but we expect the federal government to follow the law as well," Pritzker said, according to ABC News. "Safe and compassionate immigration policies, I believe, are vital. In fact, my own family owes everything to this country accepting a young refugee named Nicholas Pritzker to its shores over a century ago. As I have consistently said, violent criminals have no place on our streets, and if they are undocumented, I want them out of Illinois and out of our country."

What is a 'sanctuary city'?

There is no one concrete definition for "sanctuary cities." Nonetheless, they are often described as places where laws or policies are enacted limiting the city's cooperation with federal immigration authorities, according to immigrant rights nonprofits Global Refuge and Justice for Immigrants .

These policies can include refraining from sharing information with federal immigration law officers, restricting the ability of local police to make arrests for federal immigration violations and barring police from asking immigrants for proof of citizenship in a case where a crime was not committed.

Bart Jansen contributed to this article.