The White House is facing sharp condemnation from Democrats for its handling of the influx of Haitian migrants at the U.S. southern border, after images of U.S. Border Patrol agents on horseback using aggressive tactics went viral this week.

Striking video of agents maneuvering their horses to forcibly block and move migrants attempting to cross the border has sparked resounding criticism from Democrats on Capitol Hill, who are calling on the Biden administration to end its use of a pandemic-era authority to deport migrants without giving them an opportunity to seek asylum in the United States.

At the same time, the administration continues to face attacks from Republicans, who say Biden isn’t doing enough to deal with what they call a “crisis” at the border.

Reflecting the urgency of the political problem for the administration, Homeland Security chief Alejandro Mayorkas said Tuesday the images “horrified” him, a seeming shift in tone from a day earlier, when he and others were more sanguine about the situation at the border.

It’s a highly uncomfortable position for the administration, led by a president who has set himself up as a tonic for the harshness of his predecessor. But immigration is a complex issue, one no administration has been able to fix in decades. And Biden is trapped between conflicting interests of broadcasting compassion while dealing with throngs of migrants coming to the country — illegally — in hope of a better life.

The provision in question, known as Title 42, was put in place by the Trump administration in March 2020 to justify restrictive immigration policies in an effort to prevent the spread of the coronavirus. But the Biden administration has used Title 42 to justify the deportation of Haitian migrants who in recent days have set up an encampment in and around the small city of Del Rio, Texas. The provision gives federal health officials powers during a pandemic to take extraordinary measures to limit transmission of an infectious disease.

A federal judge late last week ruled the regulation was improper and gave the government two weeks before its use was to be halted, but the Biden administration appealed the decision Monday.

“The Biden administration pushing back on this stay of expulsions is another example of broken promises to treat migrants with respect and humanity when they reach our borders to exercise their fundamental right to asylum,” said Karla Marisol Vargas, senior attorney with the Texas Civil Rights Project and co-counsel on the litigation.

NAACP President Derrick Johnson demanded a meeting with Biden to discuss the situation and called the treatment of the Haitian migrants “utterly sickening.”

“The humanitarian crisis happening under this administration on the southern border disgustingly mirrors some of the darkest moments in America’s history,” he said in a statement.

Shortly after the judge’s decision Friday, Homeland Security officials formed a plan to begin immediately turning the groups of Haitian migrants around, working against the clock. But people kept coming.

Senate Majority Leader Chuck Schumer, an administration ally, said images of the treatment of the migrants “turn your stomach” and called on the administration to discontinue the “hateful and xenophobic” policies of Biden’s predecessor, Donald Trump.

“The policies that are being enacted now — and the horrible treatment of these innocent people who have come to the border — must stop immediately,” he told the Senate on Tuesday.

Trump essentially put a chokehold on immigration. He decreased the number of refugees admitted to a record low, made major changes to policy and essentially shut down asylum.

Biden has undone many of the Trump-era policies, but since his inauguration, the U.S. has seen a dramatic spike in the number of people encountered by border officials. The Haitian migrants are the latest example.

More than 6,000 Haitians and other migrants have been removed from the encampment in Del Rio, and Mayorkas predicted a “dramatic change” in the number of migrants there within the next two to four days as the administration continues the removal process.

As the controversy swirled around him, Biden spent his Tuesday address at the U.N. General Assembly in New York calling for the global community to come together to defend human rights and combat injustice worldwide, declaring, “the future will belong to those who embrace human dignity, not trample it.”

The remarks stood in notable contrast to images of the Border Patrol agents on horseback. Biden himself seemed to acknowledge the challenge his administration faces with immigration, offering a clipped response when asked by a reporter after his U.N. remarks to offer his reaction to the images.

“We’ll get it under control,” he insisted.

Vice President Kamala Harris also weighed in, telling reporters in Washington that she was “deeply troubled” by the images and planned to talk to Mayorkas about the situation. Harris has been tasked with addressing the root causes of migration to the U.S., and emphasized that the U.S. should “support some very basic needs that the people of Haiti have” that are causing them to flee their homes.

Videos and photos taken in recent days in and around Del Rio show Border Patrol agents confronting Haitians along the Rio Grande near a border bridge where thousands of migrants have gathered in hopes of entering the country.

One Border Patrol agent on horseback was seen twirling his long leather reins in a menacing way at the Haitian migrants, but not actually striking anyone. There was no sign in photos and videos viewed by The Associated Press that the mounted agents were carrying whips or using their reins as such when confronting the migrants.

The agents, wearing chaps and cowboy hats, maneuvered their horses to forcibly block and move the migrants, almost seeming to herd them. In at least one instance, they were heard taunting the migrants.

Asked about the images Tuesday, Mayorkas told lawmakers that the issue had been “uppermost in my mind” ever since he had seen them. He said the department had alerted its inspector general’s office and directed that staff from the Office of Professional Responsibility be present round-the-clock in Del Rio.

“I was horrified to see the images, and we look forward to learning the facts that are adduced from the investigation, and we will take actions that those facts compel,” Mayorkas said. “We do not tolerate any mistreatment or abuse of a migrant. Period.”

Previously, during a Monday news conference, both Mayorkas and Border Patrol Chief Raul Ortiz played down the incident, with Ortiz telling reporters that the agents were working in a difficult and chaotic environment and trying to control their horses.

White House press secretary Jen Psaki said Mayorkas spoke Monday before he had seen the images.

“He believes this does not represent who we are as a country and does not represent the positions of the Biden-Harris administration,” Psaki told reporters Tuesday.

Criticism was withering from members of Congress, including Rep. Bennie Thompson, a Mississippi Democrat who chairs the House Homeland Security Committee. He called on Mayorkas to “take immediate action to hold those responsible accountable.” House Speaker Nancy Pelosi also called for an investigation.

Republicans, meanwhile, stepped up their continued criticism of Biden’s approach to the border, with 26 Republican governors calling on the president to change his border policies.

“A crisis that began at the southern border now extends beyond to every state and requires immediate action before the situation worsens,” they said.