WASHINGTON — President Donald Trump on Easter Sunday appeared to rule out efforts to revive deportation protections for hundreds of thousands of young immigrants who were brought illegally to the United States as children, tweeting “NO MORE DACA DEAL!”

The president issued a series of combative statements on Twitter, centering on the Deferred Action for Childhood Arrivals program as well as the North American Free Trade Agreement, which he described as a “cash cow” for Mexico. At the same time, he railed against what he described as a dangerous lack of security on the U.S. southern border.

In a trio of tweets, Trump also asserted that Mexicans “laugh at our dumb immigration laws,” and suggested that U.S. Immigration and Customs agents were being improperly constrained from carrying out their duties.

The tone of the president’s holiday tweets differed markedly from the sentiments of goodwill commonly expressed by previous U.S. chief executives on national or religious occasions.

But frustrated by Congress’ refusal to embrace his legislative agenda and apparently egged on by conservative outlets like Fox News, the president in recent days has embraced a more freewheeling, confrontational leadership style, even by his standards.

In addition to firing two of his Cabinet members in tweets last month, Trump on Thursday gave a rambling speech in Ohio in which he surprised his own advisers by saying the U.S would soon halt military operations in Syria and suggesting he would use the upcoming nuclear talks with North Korea to extract a better trade deal with South Korea.

In his Easter tweets, Trump vented frustration over one of his campaign’s central talking points, the border wall that he repeatedly said Mexico would pay for. Congress has so far provided only limited funds for the wall project, leading Trump to reportedly weigh other avenues, including diverting money allocated to the U.S. military.

The president has made on-again, off-again efforts to use the “Dreamers” as bargaining chips in his bid to build the border wall, and he publicly vented anger over an omnibus spending measure he signed last week because it included only a small slice of funding for it.

Trump announced last fall that he would terminate the Obama-era DACA program, generating fear and panic among several hundred thousand enrollees in the program. He challenged Congress to come up with a new and better version of the program, which provides temporary protections from deportation and work permits for them.

But with the fate of the Dreamers hanging in the balance, the president then rejected a carefully crafted bipartisan immigration deal, questioning during one acrimonious meeting with lawmakers why the United States should allow immigration from Haiti and African countries he considered to be “shitholes.”

Trump is insisting that any relief for Dreamers be tied to billions of dollars for the border wall as well as strict new limits on legal immigration to the U.S. Lawmakers have been unable to agree on such a plan.

Trump on Sunday also made the puzzling assertion that “big flows” of immigrants were trying to enter the United States because of DACA. “They all want in on the act!” he tweeted.

In fact, DACA is not available to newly arrived immigrants. Although Trump terminated the program as of March, its protections remain temporarily in place under court order while legal challenges make their way through the courts.

Trump is now blaming Democrats for the collapse of DACA.

“The Democrats blew it,” he told reporters Sunday while attending Easter services with first lady Melania Trump and his daughter Tiffany Trump.

His frustration with Congress was also reflected in his call Sunday for a change in Senate rules to eliminate the use of filibusters and enable legislation to pass with just 51 votes. Republicans hold a 51-49 majority. But many of Trump’s initiatives have failed to even garner that level of support from his own party and GOP leaders oppose changing Senate rules.

Trump is also facing an array of other challenges, including the ongoing legal fight over hush money paid to adult-film actress Stormy Daniels, who says she had a sexual affair with the president more than a decade ago, and Trump’s difficulties in securing top-flight lawyers to represent him in the face of special counsel Robert S. Mueller III’s investigation of cooperation between Trump’s campaign and Russia.

On Sunday, former New Jersey Gov. Chris Christie, a former Trump campaign aide and an ex-prosecutor, warned the president against the perils of sitting down with the veteran lawman Mueller _ something Trump said he would be willing to do, although his lawyers quickly sought to walk back his offer.

“He’s a salesman, and salesmen at times tend to be hyperbolic,” Christie said on ABC’s “This Week,” referring to the president. “That’s OK when you’re working on Congress_it is not OK when you’re sitting talking to federal agents.”

Once again, the churn of turnover in Trump’s administration was a talking point on the Sunday news shows. Several major figures have jumped or been pushed out in recent weeks, including economic adviser Gary Cohn, Secretary of State Rex Tillerson, White House communications director Hope Hicks, and the head of the Department of Veterans Affairs, David Shulkin.

In a series of TV appearances Sunday, Shulkin repeated his belief that he had been ousted because he resisted attempts to privatize government-provided healthcare for veterans, an idea that has been floated by some prominent Trump backers. And Shulkin pushed back at an apparent White House attempt to portray his ouster as a resignation, not a firing _ a distinction that could stay the president’s free hand in designating an interim replacement from outside the department.

White House spokesman Lindsey Walters said Saturday that Shulkin had resigned, POLITICO reported, which does not square with his apparent firing by presidential tweet last week. In response to a direct query from interviewer Jake Tapper on “State of the Union,” Shulkin stated: “I did not resign.”

Trump has chosen as Shulkin’s successor Navy. Rear Adm. Ronny Jackson, the physician who recently offered a glowing public assessment of the president’s level of health and fitness. But Jackson faces confirmation hearings. In the meantime, the president has sought to temporarily move in a Pentagon official, Robert Wilkie, rather than allowing Shulkin’s deputy to move into the post on an interim basis.

That has raised questions about the applicability of a relatively little-known measure, the Federal Vacancies Reform Act, which gives the president powers to pick a stand-in when a Cabinet secretary is incapacitated, dies or resigns, but seemingly not when the person is fired.