Uproar grows as administration digs in on child separation policy Trump and his secretary of Homeland Security dug in on Monday.

President Donald Trump continued to defend his controversial immigration policies on Tuesday in wide-ranging comments to a business group in Washington, D.C.

Trump said that family separation at the border is caused by "crippling loopholes" in immigration law supported by Democrats.

"Under current law, we have only two policy options to respond to this massive crisis. We can either release all illegal immigrant families [of] minors who show up at the border from Central America or we can arrest the adults for the federal crime of illegal entry. Those are the only two options, totally open borders for criminal prosecution for lawbreaking. And you want to be able to do that. If we don't want people pouring into our country. We want them to come in through the process, through the legal system, and we want ultimately a merit-based system where people come in based on merit," he told the National Federation of Independent Businesses.

Multiple groups insist that the president has the power to stop family separation by ending the Justice Department's "zero-tolerance" policy that anyone who crosses the border illegally will be criminally prosecuted. Twelve Republican senators wrote to Attorney General Jeff Sessions on Tuesday afternoon, ahead of Trump's meeting with Republican lawmakers, calling on Sessions to pause family separations while Congress works on a legislative fix for the so-called loophole.

The senators, led by former Judiciary Committee Chairman Sen. Orrin Hatch, R-Utah, wrote to Sessions that the "zero-tolerance" policy was the immediate cause of the current crisis.

"We support the administration’s efforts to enforce our immigration laws, but we cannot support implementation of a policy that results in the categorical forced separation of minor children from their parents. We therefore ask you to halt implementation of the Department’s zero tolerance policy while Congress works out a solution that enables faster processing of individuals who enter our country illegally without requiring the forced, inhumane separation of children from their parents. We believe a reasonable path forward can be found that accommodates the need to enforce our laws while holding true to other, equally essential values," they wrote in the letter.

Later in his remarks, Trump said that he wants the U.S. to be a "country with heart" but that the only option is to stop people from entering the country in the first place.

"I don't want judges, I want border security. I don't want to try people. I don't want people coming in. If a person comes in and puts 1 foot in our ground, is essentially welcome to America, welcome to our country, and you never get them out," Trump said.

Trump posted multiple tweets Tuesday morning responding to criticism of his administration’s “zero-tolerance” approach to border protection.

Trump has placed the blame on Democrats, saying: “They don’t care about crime and want illegal immigrants no matter how bad they may be, to pour into and infest our Country, like MS-13.”

Senate Democrats sent a letter to Judiciary Chairman Chuck Grassley on Monday calling on him to hold a hearing on the Trump administration’s family separation policy.

“We cannot remain silent in the face of these horrifying stories,” The letter states. “We respectfully request an immediate oversight hearing to better understand the scope, nature, and impact of the Trump administration’s new ‘zero-tolerance’ policy on children and families.”

White House Communications Adviser Mercedes Schlapp insisted the administration is simply “executing the law,” and Congress has the "power to fix this."

“What’s very heartbreaking is to watch Americans who have lost their children because of the MS-13 gang members,” Schlapp said Tuesday morning, when asked about the images of children in cages and audiotape of wailing children, first obtained by ProPublica. The audio appears to capture the heartbreaking voices of Spanish-speaking children crying out for their parents.

Trump is scheduled to meet with House Republicans on Capitol Hill this afternoon to discuss two Republican-backed immigration bills amid growing calls to end practices that have separated migrant families at the southern border. Lawmakers are expected to vote on the bills this week.

Neither bill specifically deals with children separated from their parents, and the Trump administration pushed back against claims it had intentionally separated thousands of children from their parents at the U.S.-Mexico border amid accusations that it was using the children to force Congress to pass immigration reform.

"Children are not being used as a pawn," Homeland Security Secretary Kirstjen Nielsen said at a press briefing Monday. "We are trying to protect the children."

"The voices most loudly criticizing the enforcement of our current laws are those whose policies created this crisis and whose policies perpetuate it," she added.

Nielsen said she had not heard the controversial audio first published by ProPublica that made rounds on Monday, purportedly captured at a immigration detention center last week. The audio appears to capture the heartbreaking voices of Spanish-speaking children crying out for their parents.

As part of the "zero-tolerance" policy, federal prosecutors have been ordered to file criminal charges against any adult caught crossing the border illegally, including those traveling with minors. The children are being placed in the custody of the Department of Health and Human Services and adults are apprehended by law enforcement.

Critics, including top lawmakers on both sides of the aisle, have called for an immediate end to the practice, with some calling it inhumane and cruel.

Antar Davidson, a former youth care worker for a shelter in Tucson, Ariz., compared the detention centers to jails for children.

“You started getting more kids who were younger and had just recently been ripped from their parents. So as expected, they were traumatized and that was manifested in many behaviors,” Davidson said in an interview with ABC News. “Kids were throwing chairs, they were hitting employees and the employees were run ragged by these kids who were just displaying systems of trauma.

“Kinda just reacting in the only way they knew how in a situation that they had no idea what was going on,” he added.

Davidson said he quit after he was forced to tell family that they couldn’t hug each other goodbye.

“I said, ‘As a human being I can’t do that, you can do that yourself,’ to which she responded that she would report me to the shift supervisor and she preceded to try to tell [the migrants] exactly that [they couldn't hug] in Spanish and English despite them speaking Portuguese,” Davidson said recalling an alleged conversation with higher-ups at the center. “That was the beginning of the end for me. My registration came in a week later.”

ABC News' Jordyn Phelps and Mariam Khan contributed to this report.