The mayors of Boston, Chicago, Denver and New York City testified before the Republican-led House Oversight Committee Wednesday on their immigration policies.

Mayoral candidate Josh Kraft took aim at his opponent, incumbent Michelle Wu, over the weekend, blasting her for spending over half a million dollars to prepare for her grilling by the House Oversight Committee in Washington last week.

Here's a rundown of several key claims made during the hearing, and our reporting on the issues and numbers referenced by officials.

Mayors of four of the largest cities in the U.S. appeared before lawmakers in the U.S. House of Representatives on Wednesday to defend their so-called "sanctuary city" laws, which restrict local officials in helping enforce federal immigration regulations.

Fresh off the mayor’s defense of the city’s sanctuary policies and public safety record before a Congressional oversight committee, the Boston City Council held a community-based hearing where advocates pushed for expansion of the Trust Act.

A GOP-led committee questioned mayors Wednesday on their limited cooperation with federal immigration authorities. Boston's Mayor Wu has argued the policy keeps the city safe and builds trust with diverse communities.

Boston Mayor Michelle Wu stood by her decision to spend well over half a million taxpayer dollars to prepare for