Border wall prototypes on display in San Diego, where contractors offer different designs. Elliott Spagat/AP hide caption

Immigrants suspected of being in the U.S. illegally are transferred to be processed at the Tucson sector of the U.S. Customs and Border Protection headquarters in Arizona in 2016. Ross D. Franklin/AP hide caption

Citizenship candidates wait for a naturalization ceremony to begin in downtown Manhattan on July 2, 2013 in New York City. U.S. Mario Tama/Getty Images hide caption

Nikolas Cruz appears in court for a status hearing in Fort Lauderdale, Florida. Mike Stocker/AP hide caption

Missouri Gov. Eric Greitens during an interview at the Missouri Capitol in January 2018 after his extramarital affair was exposed. Jeff Roberson/AP hide caption

Broward, Fla., Sheriff Scott Israel speaks to reporters after the shootings at Marjory Stoneman Douglas High School where 17 people were killed on February 15, 2018. Mark Wilson/Getty Images hide caption

People wave U.S. flags during a 2017 naturalization ceremony at the Los Angeles Convention Center. Jae C. Hong/AP hide caption

A vigil after the fatal shooting at Marshall County High School on Thursday, Jan. 25, 2018, in Benton, Ky. Robert Ray/AP hide caption

Students of Marjory Stoneman Douglas High School gather on Thursday in Parkland, Fla. Fourteen students and three staff members were killed in a shooting at the school on Wednesday. Mark Wilson/Getty Images hide caption

Broward County Public Schools Superintendent Robert Runcie speaks at a news conference Thursday, as county Mayor Beam Furr (from left), Broward Sheriff Scott Israel, Gov. Rick Scott and FBI agent Robert Lasky look on. Mark Wilson/Getty Images hide caption

Parents wait for news after a shooting at Marjory Stoneman Douglas High School in Parkland, Fla., on Wednesday. Officials say 17 people were killed and a suspect is in custody. Joel Auerbach/AP hide caption

Protesters marched in Washington, D.C., in September in support of the Deferred Action for Childhood Arrivals program. Matt York/AP hide caption

A man walks past a Baltimore police patrol car. Patrick Semansky/AP hide caption

The GEO Group's immigrant detention facility in Aurora, Colo., where detainees are challenging forced work rules. David Zalubowski/AP hide caption

Defense Secretary Jim Mattis pictured speaking at the White House Wednesday. He said Thursday that "DREAMers" in the military won't be deported. Carolyn Kaster/AP hide caption