President Trump moved aggressively Friday to take ownership of an internal White House plan to release immigrant detainees into “sanctuary cities” that his aides had sought to minimize a day earlier by saying it was shelved months ago after only informal consideration.

Directly contradicting his staff, Trump declared in a tweet that he was giving the plan “strong considerations,” and, at an event later in the day, he sarcastically challenged Democrats in liberal jurisdictions to accept the immigrants with “open arms.”

The president said that if Congress refuses to change immigration laws to allow his administration to more quickly deport a surge of asylum-seeking Central American families, “we’ll bring – I call them the ‘illegals’ because they enter the country illegally – to sanctuary cities and areas and let those particular areas take care of it.”

Specifically referring to California Gov. Gavin Newsom, D, and House Speaker Nancy Pelosi, D-Calif., Trump added: “California is always saying, ‘We want more people.’ We can give them a lot. We can give them an unlimited supply. Let’s see if they’re so happy.”

Since 1989, San Francisco has had policies aimed at limiting municipal cooperation with federal immigration authorities in certain cases, and California in 2017 adopted a “sanctuary state” law that implemented similar restrictions.

Trump’s comments capped a frenzied two-week period during which the president threatened to close the U.S. border with Mexico only to pull back amid warnings such a move would deeply harm the economy. He then embarked on an overhaul of the leadership of the Department of Homeland Security that included the removal of Secretary Kirstjen Nielsen and a promise to staff the agency with people who would take a “tougher” approach on immigration.

The president’s embrace of the sanctuary cities policy is another sign of his mounting frustration over his inability to stem the flow of migrants at the border after making a promise to crack down on illegal immigration the central theme of his 2016 campaign.

Due to the fact that Democrats are unwilling to change our very dangerous immigration laws, we are indeed, as reported, giving strong considerations to placing Illegal Immigrants in Sanctuary Cities only….

— Donald J. Trump (@realDonaldTrump) April 12, 2019

The Washington Post reported Thursday that the administration had been eyeing districts of political adversaries, including that of Pelosi, to release detainees. The disclosure of the plan – which was explicitly rejected in November and February by Homeland Security officials who feared it would create additional burdens for agents and potentially run afoul of legal provisions – drew widespread recriminations.

A White House official said Thursday that the proposal “was just a suggestion that was floated and rejected, which ended any further discussion.”

But on Friday, White House aides, according to people familiar with the discussions, began a new, preliminary review of whether there could be a way to move detainees to sanctuary cities should Trump decide to actually go through with the plan. A DHS official said the agency had not been instructed to move forward.

One senior aide described Trump’s position as an effort to exploit the political “upside” of the controversy and draw a sharp contrast with Democrats on border enforcement. Trump’s eagerness to do so reflected his confidence that coaxing his rivals into a deeper fight over immigration will help him in his 2020 reelection campaign.

Several aides said that there was a desire among some West Wing officials to move away from immigration after a week in which the president fired several senior DHS leaders in a sign of growing alarm over the spiking border crossings.

But Trump “wants to talk about it and will always take whatever position he thinks makes him look strongest,” said a senior administration official, who like other aides spoke on the condition of anonymity to discuss private deliberations.

Administration officials said that even Stephen Miller, the president’s hawkish immigration aide, was concerned Thursday about the plan getting out and had tried to downplay it in the building. Communications officials, including press secretary Sarah Sanders and her deputy Hogan Gidley, sought to convince reporters that it was not under consideration anymore to keep the story from picking up traction.

But after seeing media coverage of the plan Friday morning, the president decided it was a good idea and he tweeted out his support, according to aides.

One person outside the White House who frequently talks with the president said that while Miller is widely viewed as the most forceful advocate for hard-line border policies that have, in numerous instances, been halted by federal courts, it is Trump who is most willing to “push the limits.”

During a trip to the border town of Calexico, Calif., last week, Trump reportedly told then-Customs and Border Protection Commissioner Kevin McAleenan he should close the border, despite the president having said earlier in the week he would keep it open, according to CNN and the New York Times. He then told McAleenan, who is now the acting Homeland Security secretary, that he would pardon him if he ran into any legal problems resulting from the closure, although it was unclear how serious he was, according to the reports.

“At no time has the President indicated, asked, directed or pressured the Acting Secretary to do anything illegal,” a DHS spokesman said in response to a question about the conversation between Trump and McAleenan. “Nor would the Acting Secretary take actions that are not in accordance with our responsibility to enforce the law.”

A senior administration official said Trump has periodically mused about closing the border, even after saying he wouldn’t, but added that they don’t think he is seriously considering the move. “He’s just frustrated as hell,” the official said.

In his remarks at the White House on Friday, Trump vowed to send more military troops to the border, after having dispatched several thousand to support Border Patrol operations last fall ahead of the midterm election. Troops are not allowed under U.S. law to make arrests inside the United States, and they were confined to a support role, including such duties as erecting barbed wire.

“There are a lot of people with criminal records trying to get through,” Trump said of the migrants, even though a majority are families with children.

DHS said 103,000 migrants, including nearly 60,000 family members, were taken into custody in March at the southern border with Mexico, a sharp increase from the total of 58,000 migrants detained in January.

House Democrats have begun internal discussions about launching an investigation into Miller’s role in the White House’s immigration policies, including potentially calling him to testify on Capitol Hill. Rep. Kathleen Rice (D-N.Y.), who chairs the House Homeland Security Committee, said Miller needs to “make his case for these terrible policies to the American people instead of being this shadow puppeteer.”

“If he’s going to continue advocating for these policies and personnel change then he needs to come before the American people and explain himself,” Rice said.

She added that the committee’s leadership might soon request emails and documents from the White House and federal agencies that could shed light on Miller’s role. Though his name was not on messages sent from the White House to pressure DHS to release immigrants into sanctuary cities, some agency officials said they believed he was among those who had initiated the request.

“Using human beings – including children – for perceived political gain, is reprehensible,” Sen. Kamala D. Harris (D-Calif.), who is campaigning for the Democratic presidential nomination, wrote on Twitter.

“It is just grotesquely corrupt,” Sen. Richard Blumenthal (D-Conn.) said in an interview Friday. “Put aside the cruelty and inhumanity of using asylum seekers as pawns to retaliate against political foes. It is a profound betrayal of American values.”

Blumenthal accused Trump of “weaponizing innocent families who are struggling to survive.”

The White House proposal had been opposed by federal immigration enforcement officials who viewed it as unworkable, having no legal justification and likely to create strain on an agency already dealing with a crisis.

DHS generally releases immigrants in two ways: directly from one of Immigration and Customs Enforcement’s immigration jails or, more recently, from Customs and Border Protection after they are apprehended and pass an initial security check.

ICE is required to release immigrants, including some with serious criminal records, if they cannot deport them. The U.S. Supreme Court ruled in 2001 that immigrants cannot be jailed indefinitely after they have a final deportation order and must be released after six months if their native country will not take them back.

Sometimes ICE officers or immigration judges release immigrants on bond. Under current practice, once detainees are released, they are generally free to settle wherever they choose, and they are required to inform the government of their address.

Most of the roughly 50,000 immigrants in federal custody have been apprehended at the southern border.

On Friday, San Francisco District Attorney George Gascón said the president was engaged in “a politically motivated stunt.”

“The fact that such a proposal is being peddled by the leader of the free world is an all-time low for American discourse,” he said. “And it’s the clearest sign yet that the president fully intends to chart a path to reelection on the back of racist rhetoric and policies intended to divide us.”