Watch Live: DHS Secretary Alejandro Mayorkas testifies before lawmakers as migrant surge grows

Washington — Homeland Security Secretary Alejandro Mayorkas will face tough lines of questioning from lawmakers when he appears before Congress on Wednesday for the first time since being confirmed as the head of overseeing a sprawling department charged with managing some of the nation's most urgent challenges. What: Homeland Security Secretary Alejandro Mayorkas testifies before the House Homeland Security Committee  Date: March 17, 2021 Time: 9:30 a.m. Location: U.S. Capitol Online stream: Live on CBSN in the player above and on your mobile or streaming device.

Chief among them is a historic number of migrants who are illegally crossing into the United States, creating an overwhelming need for more humanitarian assistance along the Texas border with Mexico, where more than 13,000 unaccompanied migrant children are now in U.S. custody, sources tell CBS News. The U.S. is on pace to stop more migrants encountered along the border than at any point in the last 20 years, Mayorkas said in a statement released Tuesday, repeatedly calling the situation "difficult."