Democrats sharpened their attacks on the Trump administration's handling of the migrant crisis on the U.S.-Mexico border on Wednesday, saying human rights were being neglected and demanding the firing of the Border Patrol's leadership.

U.S. lawmakers, officials and rights activists who have visited migrant detention centers along the border describe nightmarish conditions marked by overcrowding and inadequate access to food, water and other basic necessities.

The Department of Homeland Security's inspector general on Tuesday described dangerous conditions in migrant-holding centers in Texas' Rio Grande Valley, publishing graphic photos of cells holding twice as many people as they were built for.