Kentucky Rep. James Comer, the Republican who chairs the House Oversight Committee, confronted four Democratic sanctuary city mayors on Wednesday over their refusal to fully cooperate with Immigration and Customs Enforcement.

The Democratic mayors of New York, Denver, Boston, and Chicago fended off a barrage of questions from House Republicans who accused them of protecting criminals and jeopardizing President Donald Trump’s plan to deport millions of undocumented immigrants.

Republican members of Congress hammered four Democratic mayors about their so-called sanctuary city policies, accusing them of endangering Americans and threatening to prosecute local officials.