Donald Trump said Wednesday he is considering issuing an executive order to get rid of the longstanding measure that guarantees citizenship to those born within the borders of the U.S.

'We're looking at that very seriously,' Trump told reporters before departing the White House to speak to veterans in Kentucky.

It was part of a free-wheeling question-and-answer session on the South Lawn which also saw him blast the prime minister of Denmark as 'nasty' for calling his offer to buy Greenland 'absurd'; proclaim himself 'the chosen one' as he boasted about his China trade war; appear to ditch tax cuts and embrace background checks on guns having done the opposite the day before; and accuse Barack Obama of being 'outsmarted' by Vladimir Putin when the Russian strongman seized Crimea.

The attempt to tackle birthright citizenship - or 'anchor babies' - came as his acting Homeland Security secretary said he would publish a new role on Friday to allow illegal immigrant children to be indefinitely detained, and it was reported by NBC News that states or cities will be allowed to refuse to resettle refugees there.

The president said the current understanding of the constitution - that virtually every child born in the U.S. or its territories is automatically a citizen - is 'ridiculous' because non-citizens are able to cross over the border just to have children that could then be deemed U.S. citizens.

'Birthright citizenship – where you have a baby in our land,' Trump explained. 'You walk over the border, have a baby, congratulations – the baby is now a U.S. citizens. We're looking at it very, very seriously.'

Trump appeared surprised that a reporter was aware that he was re-upping consideration of signing an executive order on birthright citizenship, a scheme which had been talked about last year.

'I don't know how you found that out, but that's very good,' Trump praised. 'We're looking at birthright citizenship very seriously. It's frankly ridiculous.'

Donald Trump said Wednesday he is again considering an executive order that would abolish the 'ridiculous' birthright citizenship

The president floated the idea of doing away with the constitutional measure last year as well

This is not the first time the president has floated abolishing birthright citizenship.

Last year, during the months leading up to the midterm elections, Trump said he was preparing an executive order to nullify the constitutional guarantee in the 14th amendment.

'We're the only country in the world where a person comes in and has a baby, and the baby is essentially a citizen of the United States for 85 years, with all of those benefits,' Trump said in an interview released in October 2018. 'It's ridiculous. It's ridiculous. And it has to end.'

Trump's biggest campaign promise was to crack down on illegal immigration and build a wall to stop people from unlawfully crossing the border and living off of U.S. benefits. He also said during the 2016 campaign that he would do away with birthright citizenship for the children of undocumented immigrants.

Last week the administration announced a new 'public charge' rule that would allow the government to deny entry to individuals it felt would likely end up relying on Medicaid, food stamps or other public benefits.

Reconsideration of the executive order also comes the same day the Department of Homeland Security rolled out a new plan that would allow the government to indefinitely detain migrants children.

Acting Homeland Security Secretary Kevin McAleenan said the rule would finally replace the Flores Settlement Agreement, which stops children – and by extension their parents – from being detained for more than 20 days.

The first time around Trump tried to bring up the executive order, it was met with backlash – even from those within the Republican Party.

'You obviously cannot do that,' now-retired House Speaker Paul Ryan said in 2018.

With the crackdown on illegal immigration, it's likely that Trump could now move forward on the executive order he never acted on last year.

Vice President Mike Pence pushed back, claiming that the language of the constitution was not clear on if the 14th Amendment, which addresses citizenship, was referring to the children of those who were in the U.S. illegally.

'We all cherish the language of the 14th Amendment, but the Supreme Court of the United States has never ruled on whether the language of the 14th Amendment — 'subject to the jurisdiction thereof' — applies specifically to people who are in the country illegally,' Pence said in a 2018 interview, just hours after Trump's comments on a potential executive order were reported.

The president cannot override amendments to the Constitution by executive order.

They can only be changed or undone with an overwhelming majority of two-thirds in both chambers of Congress or through a constitutional convention called by two-thirds of state legislatures.

However the measure appeared to be a deliberate attempt to highlight Trump's hardline immigration agenda.

Shortly before Trump's South Lawn intervention, the Department of Homeland Security's acting boss announced it is issuing a new rule this week which it claims will allow it to indefinitely detain migrant children and their parents who cross the border illegally,.

Acting Homeland Security Secretary Kevin McAleenan said the rule would finally replace the Flores Settlement Agreement, which stops children – and by extension their parents – from being detained for more than 20 days.

But it faces an instant legal battle because a federal judge must agree to tearing up the Flores settlement, with immigrant groups already preparing for a fight which is likely to end up in the Supreme Court.

Donald Trump hailed the rule, which will not be published until Friday, as the end to 'catch and release' immigration practices, and McAleenan claimed it would be a significant deterrent to illegal immigration.

During a press conference Wednesday, McAleenan said the so-called 'Flores Final Rule' would keep families together during immigration proceedings, and prevent children from becoming a 'pawn' to those who just wish to game the system.

'No child should be a pawn in a scheme to manipulate our immigration system, which is why the new rules eliminate the incentive to exploit children as a free ticket or… a passport for migration to the United States,' McAleenan said.

Acting Homeland Security Secretary Kevin McAleenan said the new rules would prevent human smugglers and illegal border crossers from using children as 'pawns' or 'passports' to gain entry and release into the U.S.

By quoting the National Border Patrol president, Trump insisted the rules would stop 'catch and release' immigration practices

THE RULES ON DETAINING ILLEGAL MIGRANT KIDS TRUMP WANTS TO CHANGE Since 1997, what happens to children who cross the border illegally has been determined by a court settlement made by the Clinton administration to end a long-running case brought on behalf of a group of children detained at the border in 1985. It got its name from one of them - Jenny Lisette Flores - and when the Clinton administration ended the federal litigation by negotiation, became known as the Flores Settlement. It set a 20 day limit on detaining children, and said that they had to be released to their parents or suitable guardians. The federal government has to offer 'food and drinking water as appropriate,' 'medical assistance if minor is in need of emergency services,' 'toilets and sinks,' 'adequate temperature control and ventilation,' 'adequate supervision to protect minors from others,' 'contact with family members who were arrested with the minor and separation from unrelated adults whenever possible.' If a relative or guardian could not be found, they had to be sent to homes, not other detention centers - 'the least restrictive environment possible,' the agreement specified. The settlement was temporary, And it contained a poison pill: the only way to end the settlement was to come up with formal immigration rules which met the minimum conditions in the settlement and to which the federal court overseeing the settlement agreed. Since then it has been back in court repeatedly, with the Bush and Obama administration accused of breaching it. This month a judge ruled that it guarantees that detained children have a right to toothpaste, after the Trump administration suggested it was optional. THE CHANGE The Homeland Security department did not publish the details of its new rule Wednesday but claimed it would be a full-scale replacement of Flores which would allow indefinite detention. That would mean it has to embrace the other aspects of Flores - meaning the conditions under which children are kept will have to be as described in the deal and subsequent rulings. How the Department of Homeland Security thinks it will get indefinite detention passed is unclear. Advertisement

The new rules, he claims, should appeal to those who have decried the immigration enforcement system for breaking up parents and children.

'Our goal remains, as in the previous administration, to provide an expeditious immigration results, while holding families together, which particularly benefits legitimate asylum seekers with meritorious claims,' McAleenan said, claiming all migrants were left in a state of limbo for years under the current rules.

Democrats are already pushing back against the rules rollout, claiming the president is trying to justify 'child abuse.'

'The Administration is seeking to codify child abuse, plain and simple,' House Speaker Nancy Pelosi said in a statement Wednesday. 'Its appalling, inhumane family incarceration plan would rip away basic protections for children's human rights, reversing decades-long and court-imposed rules and violating every standard of morality and civilized behavior.'

Instead of improving the situation with families and minor migrants, Pelosi insists that indefinite detention would 'compound the cruelty' already exhibited in holding facilities at the border.

She also mentioned the 'worsening conditions for children already forced to sleep on concrete floors, eat inedible food and be denied basic sanitation and standards of care,' which immigration officials claim is due to the influx in family apprehensions.

McAleenan blamed the more than 450 per cent increase in family unit apprehension this year on the 2015 reinterpretation of the Flores agreement, which led to the rules that required children and their parents be released in 20 days.

The Flores agreement established that when families with children were captured and detained, they had to be released in less than two dozen days to a family member or guardian in the U.S. – and if that was not possible they had to be transferred to a care facility that does not operate like a jail.

The Trump administration insists the limits set by Flores has encouraged illegal immigrants to arrive at the border with children with the expectation of being swiftly released.

'Brandon Judd, President, National Border Patrol Council. 'This will effectively end Catch and Release and curb illegal entries,'' Trump posted to his Twitter Wednesday, quoting the Border Patrol Council president.

In 2018, the administration proposed a similar plan to this one, but the rules were never enacted as there was an influx of migrants arriving at the border and a shortage of bed space.

Although there was a massive dip in illegal border crossing during Trump's first year in the White House, the frequency spiked in late 2018, and border agents and officials lamented they were not prepared for the influx, leading to overcrowding and unsanitary conditions at many detention facilities.

As of May 2019, there were at least seven documented instances where children died from illness complications after being held in some of these centers.

The rationale for the rules proposed in September 2018 was that the government should be permitted to detain children for longer so they could be treated with 'dignity, respect and special concern for their particular vulnerability as minors,' as required by the Flores agreement.

It seems the 2018 plan is being reupped now that there has been a drop in border crossings in recent weeks and border facilities are less overwhelmed.

The dip comes after Trump made an agreement with the Mexican President Andrés Manuel López Obrador for the government to deploy Mexican security forces to help crack down on asylum seekers on their side of the border.

It's likely the rules, which again seeks to 'terminate' some of the restrictions in Flores, will be challenged in court.