Updated at 5:15 p.m. with homeland security chief comments and Ted Cruz proposal to process asylum claims faster.

WASHINGTON -- The Trump administration doubled down Monday on a new zero-tolerance policy of pressing criminal charges against anyone caught crossing the border, then separating children from parents for weeks or months as those cases work through the courts.

Nearly 2,000 children have been taken from adult migrants in the six weeks after the policy began -- most, by all accounts, ordinary job-seeking migrants. As outrage boiled, critics in both parties denounced the separations as inhumane, and the president and top aides continued to insist that they had no option.

"Illegal actions have and must have consequences. No more free passes. No more get out of jail free cards," said Kirstjen Nielsen, secretary of homeland security.

At a White House meeting on space policy, President Donald Trump declared that "the United States will not be a migrant camp and it will not be a refugee holding facility. It won't be." As for "child separation," he professed a lack of options, insisting that "we're stuck with these horrible laws."

Hours earlier he deflected criticism by insisting on Twitter that "children are being used by some of the worst criminals on earth as a means to enter our country."

Two previous presidents did not choose to charge every person caught crossing the border without permission with a crime, however. The issue has erupted as a major point of contention between Democrats and Republicans, in Congress and ahead of the midterm elections in November.

With pressure mounting from across the political spectrum, Nielsen and Attorney General Jeff Sessions defended the family separation policy to the National Sheriffs Association in New Orleans. Nielsen flew back to Washington to field questions at a Monday afternoon White House news briefing as Trump aides scrambled to tamp down the uproar.

"As long as illegal entry remains a criminal offense, DHS will not look the other way," Nielsen said.

Children are being used by some of the worst criminals on earth as a means to enter our country. Has anyone been looking at the Crime taking place south of the border. It is historic, with some countries the most dangerous places in the world. Not going to happen in the U.S. — Donald J. Trump (@realDonaldTrump) June 18, 2018

It is the Democrats fault for being weak and ineffective with Boarder Security and Crime. Tell them to start thinking about the people devastated by Crime coming from illegal immigration. Change the laws! — Donald J. Trump (@realDonaldTrump) June 18, 2018

Cruz legislation

Late Monday afternoon, Texas Sen. Ted Cruz announced that he will push legislation to end the separations -- by hastening deportations.

Cruz defended the policy of family separation in recent days, echoing the administration's argument that anyone charged with a crime -- whether immigration related or a crime such as burglary -- would be jailed pending trial, and defendants can't keep children with them in jail.

On Sunday, Cruz's challenger, Rep. Beto O'Rourke, D-El Paso, led a protest march at the Tornillo tent camp 40 miles outside of El Paso, where federal authorities have been housing children detained at the border.

Cruz's proposal would keep families together but try to expedite the legal process in immigration courts.

"All Americans are rightly horrified by the images we are seeing on the news, children in tears pulled away from their mothers and fathers. This must stop. Now," he said in a statement. His proposal would mandate resolution of immigration cases within 14 days. Court rulings allow families to remain together in detention for up to 20 days.

"Those who meet the legal standard should be granted asylum and those who don't should be immediately returned to their home country," Cruz said.

A Quinnipiac University poll released Monday found that 66 percent of Americans oppose the family separation policy, with only 27 percent in favor it. The poll found the only group supporting the policy was Republican voters, at 55 percent for and 35 percent against. Pollsters said Republican voters were the only listed party, gender, education, age or racial group to support it.

Trump pressured

Pressure on Trump came from some unusual corners.

First lady Melania Trump seemed to distance herself from his enforcement policy, with an aide telling CNN on Sunday that "Mrs. Trump hates to see children separated from their families and hopes both sides of the aisle can finally come together" to address the problem.

Former first lady Laura Bush penned an op-ed column denouncing family separation as "cruel."

"We share the concern. The president himself said he doesn't like this process," White House press secretary Sarah Huckabee Sanders said. "We're not the ones responsible for creating this problem."

Nielsen insisted that asylum seekers can lawfully request asylum by presenting themselves at a port of entry, rather than entering the United States illegally and then requesting asylum, which subjects them to criminal prosecution.

But some refugees have been turned away at ports of entry, and barred from requesting asylum even though U.S. law gives them that right.

You can’t simultaneously argue that family separation isn’t happening, that it’s being used as a deterrent, that the Bible justifies it and that it’s @TheDemocrats fault. @POTUS is not being served well by his advisors on this issue. — Anthony Scaramucci (@Scaramucci) June 18, 2018

Sen. Ben Sasse of Nebraska was among the Republicans who most forcefully criticized Trump.

"The President should immediately end this family separation policy," he wrote on Facebook, rejecting the assertion that only Congress can end "the horrors of family separation."

"The administration's decision to separate families is a new, discretionary choice," Sasse wrote. "Anyone saying that their hands are tied or that the only conceivable way to fix the problem of catch-and-release is to rip families apart is flat wrong."

Cornyn also proposing legislation

Sen. John Cornyn of Texas, the deputy majority leader, stopped short of blaming the administration for the family separations but did call on Congress to stop the policy by changing the laws about family detention.

"We have to keep family members together and prevent unnecessary hardship, stress, and outrage," Cornyn said on the Senate floor. "Parents who are awaiting court proceedings shouldn't have to do so separated from their children, and children shouldn't be taken from their parents and left frightened and confused about where they are and what is transpiring around them."

Cornyn later said in a news release he plans to reintroduce an updated version of legislation he pushed in 2014 that would mitigate the problem of family separation while improving the immigration court process for unaccompanied children and families apprehended at the border.

Trump has repeatedly -- and falsely -- blamed Democrats for the family separation policy. Nielsen contradicted the assertion on Monday when she conceded that the current administration had decided to enforce immigration laws in ways the last two presidents refused to.

The only two choices, she said, would be to charge people who enter the country illegally with a crime, in which case separation from children traveling with them would be inevitable and mandatory, or ignoring the criminal infraction.

Sessions policy

Sessions unveiled the zero-tolerance policy in May, touting it as a deterrent to illegal immigration.

He defended the policy last week on biblical grounds, citing Romans 13, which instructs the faithful to obey civil law. Religious leaders have condemned family separation, and his own United Methodist denomination chided him for glossing over many other biblical teachings, including kindness to strangers.

On Monday, speaking to the nation's sheriffs at a gathering in New Orleans, Sessions again defended zero tolerance.

"We do not want to separate children from their parents. We do not want adults to bring children into this country unlawfully, placing them at risk," he said. "But we do have a policy of prosecuting adults who flout our laws to come here illegally instead of waiting their turn or claiming asylum at any port of entry."

Trump plans to meet Tuesday with House Republicans to discuss legislation aimed at providing a long-term solution to the issue of Dreamers and the Deferred Action for Childhood Arrivals.

The Obama- era policy shielded young immigrants from deportation if they were brought to the country as minors. Trump scrapped that policy last fall, though federal courts have kept the program in place temporarily.