Facing an ever-widening swath of criticism, including from senior Republicans, Trump administration officials dug in Monday on their decision to separate migrant parents and children at the U.S.-Mexico border, signaling they will only end the practice if lawmakers pass immigration legislation.

“Congress and the courts created this problem, and Congress alone can fix it,” Homeland Security Secretary Kirstjen Nielsen said during a contentious press briefing at the White House. “Until then, we will enforce every law we have on the books to defend the sovereignty and the security of the United States.”

Administration officials contradicted President Donald Trump on Monday by pointing to a 2008 law passed overwhelmingly by both chambers and signed into law by GOP President George W. Bush. Nielsen even noted that when asked about an op-ed opposing the family separation policy penned by Bush’s wife, former first lady Laura Bush.

Trump has blamed Democrats repeatedly, though, despite the Bush imprimatur and current Republican control of the government. In recent days, he has alluded to an unnamed bill Democrats passed on their own that presumably was signed by an unnamed Democratic president, all without naming anyone.

On Monday, his senior aides referred to the 2008 Trafficking Victims Protection Reauthorization Act. It passed unanimously and quickly got Bush’s signature.

“Congress passed a law,” a defiant Nielsen said Monday. “Congress can fix this tomorrow.”

Administration officials initially called their policy of separating children a deterrent for others looking to come here or smuggle children into the United States. Days later, amid a public firestorm, they shifted to a message of enforcing the law where previous administrations refused to do so.

Nielsen called on lawmakers to change immigration laws if they are concerned about children being separated from adults at the U.S. border, contending there is no separation if officials can determine the parents are the parents. When Congress asks the executive branch to ignore the laws it passed, she said, it is the “beginning of the unraveling of democracy.”

Nielsen claimed a 314 percent hike in recent months in groups showing up at the southern border falsely claiming to be families.

“Let’s fix it,” she said, sending a message to Congress.

“Many” of the loopholes that lead to migrant children and parents being separated at the southern border are included in one or both of the House GOP immigration overhaul bills that could hit the floor as early as this week, Nielsen said. If either becomes law, “then the families will stay together during the proceedings,” she said, referring to the prosecution those adults individuals trying to cross the border illegally must go through.

Upon taking questions at the briefing, though, Nielsen quickly faced tough questions, including how the current practice was not child abuse or akin to the internment of Japanese Americans during World War II. At one point, someone played a ProPublica video on their mobile device depicting the cries and screams of children who were being separated from parents or adults who brought them to the border.

Parents from Central and South American countries sent most — 10,000 of the 12,000 — of the children now in U.S. federal custody to the U.S.-Mexico border with “strangers,” Nielsen claimed, saying ending the separation policy would help only smugglers, human traffickers and violent organizations like the MS-13 gang.

As the president readies for a Tuesday afternoon meeting on Capitol Hill with House Republicans to discuss two immigration measures, some are joining congressional Democrats in calling for an end to the policy.

Rep. Kevin Yoder, R-Kan., chairman of the House Homeland Security Appropriations Subcommittee, on Monday urged Attorney General Jeff Sessions to end the separation policy.

“As the son of a social worker, I know the human trauma that comes with children being separated from their parents,” he said in a statement. “It takes a lasting, and sometimes even irreversible toll on the child’s well being. That’s why I’m demanding that Attorney General Sessions halt the practice of family separation at the border immediately as Congress works toward legislative solutions.”

House Minority Leader Nancy Pelosi, D-Calif., called the policy “barbaric” and a “dark stain on our nation.”

All Senate Democrats have backed a bill to address the practice, and Texas GOP Sen. Ted Cruz announced he will introduce his own bill.