Washington (CNN) The rapid halting of President Donald Trump's immigration order has given him his first exposure to the limits on his presidential power, a sharp awakening for a real estate mogul accustomed to the wide unilateral prerogative of a chief executive.

With the order mired in legal challenge and travelers again weighed with uncertainty, Trump is facing his first run-in with a system of federal checks and balances.

The fresh uncertainty over the order illustrated again the chaotic fallout of the new President's intent in rapidly fulfilling his most controversial campaign promises.

And for the second Saturday in a row, airlines, travelers, and government lawyers are confronting a broad shift in the rules governing US immigration, sowing further global confusion about the President's travel ban meant to combat terror.

Aides scramble

Trump was mingling among guests in the living room of his lavish Florida estate on Friday when a judge in Washington state halted enforcement of his executive order, which he signed last Friday at the Pentagon.

His core team of advisers, including chief of staff Reince Priebus, chief strategist Steve Bannon and his top policy aide Stephen Miller, had all made the journey with him to Palm Beach on Air Force One, where he's spending the weekend at his Italianate Mar-a-Lago club. The group triaged the judge's ruling from there.

Back in Washington, Trump's press secretary, Sean Spicer, issued a statement around 10 p.m. ET Friday night announcing the Justice Department intended to "file an emergency stay of this outrageous order and defend the executive order of the President." He updated his language moments later to remove the word "outrageous."

But if the White House was hoping to temper its language around the legal challenge, the President himself dashed any hope of decorum when he woke up at his oceanfront retreat on Saturday.

"The opinion of this so-called judge, which essentially takes law-enforcement away from our country, is ridiculous and will be overturned!" Trump wrote on Twitter.

JUST WATCHED President's response to restraining order Replay More Videos ... MUST WATCH President's response to restraining order 03:49

Drafted by a small circle of aides, who kept the contents secret from lawmakers and most government officials, the contentious ban has drawn legal scrutiny since it went into effect last weekend. At the Justice Department, the acting attorney general was fired from her post on Monday night after telling agency lawyers not to defend the measure. Trump replaced her with a US attorney who vowed to enforce the ban.

But with the judge's ruling on Friday evening, even Trump's own appointees will be forced to follow the court's order. Less than three hours after the decision was handed down, Customs and Border Protection officials told representatives from major air carriers they could allow previously banned passengers to board flights bound for the US.

The Department of Homeland Security, headed by Trump pick John Kelly, said it is suspending implementation of the order, even as it insisted the ban was "lawful and appropriate."

JUST WATCHED Homeland Security suspends travel ban process Replay More Videos ... MUST WATCH Homeland Security suspends travel ban process 01:57

And the State Department, run by Trump appointee Rex Tillerson, said it is revalidating visas it revoked only days ago.

"We have reversed the provisional revocation of visas under Executive Order 13769," an agency official said. "Those individuals with visas that were not physically cancelled may now travel if the visa is otherwise valid."

The order and its subsequent reversal have led to rapid-fire changes in US policy, leading some to view a government in disarray.

"I cannot remember a president who has had so much chaos surrounding his presidency in the first 100 days," said David Gergen, a White House adviser to four presidents and now CNN senior political analyst. "I understand they were trying to address a serious concern they had. They brought this on themselves the way they drafted this. They didn't have the lawyers. They need to vet this in a way to pass constitutional muster."

Impact on Gorsuch nomination

The latest legal controversy -- and Trump's highly unusual step for a President of personally attacking a judge who delivered a ruling critical of his administration -- could spark new controversy and ammunition for Democrats in the fight against his nomination of Judge Neil Gorsuch for the Supreme Court.

Senate Democratic Minority Leader Chuck Schumer made clear on Saturday that the President's tweet branding Judge James Robart as a "so-called judge" would prompt difficult questions for Gorsuch at his confirmation hearing.

"The President's attack on Judge James Robart, a Bush appointee who passed with 99 votes, shows a disdain for an independent judiciary that doesn't always bend to his wishes and a continued lack of respect for the Constitution, making it more important that the Supreme Court serve as an independent check on the administration," Schumer said in a statement.

JUST WATCHED Trump: 'Go nuclear' on Supreme Court pick Replay More Videos ... MUST WATCH Trump: 'Go nuclear' on Supreme Court pick 05:05

But Vice President Mike Pence made clear in a speech to the Federalist Society in Philadelphia on Saturday that the White House would respond to any attempt to use the Senate filibuster to block Gorsuch's nomination by urging Senate Majority Leader Mitch McConnell to enact the so-called nuclear option to change the chamber's rules to allow GOP senators to schedule a vote on his nomination with a simple majority.

Still, the likelihood that the tussle over the legality of Trump's executive order sooner or later ends up in the Supreme Court gives Democrats a fresh rationale to do everything possible to delay his confirmation, given that the Supreme Court, currently operating one justice short, may not be able to amass a majority in support of the President's move.

Airlines adjust

Just as they did last Saturday as the order went into effect, airlines are adjusting their procedures for allowing passengers onto planes bound for American airports, and travelers who were previously banned are assessing whether to again attempt travel to the US.

Opponents of the ban said they were heartened by the reversal. But there remained little certitude for US policy going forward.

"Our concern is for the welfare and safety of those vulnerable refugees who believed they were escaping danger and the indignity of their lives to be resettled in the US -only to have their hopes curtailed," said Leonard Doyle, a spokesman for the International Organization for Migration. "Until there is further clarity, we would not wish to see the hopes of refugees raised only to be subsequently disappointed."

At the Dubai International Airport, passengers boarding flights reported business as usual, as calm lines formed at counters in the terminal where US-bound planes depart. Passengers at Istanbul's Ataturk Airport and London Heathrow reported similar scenes.

Major airlines — including Qatar Airways, Lufthansa, and Air France — said on Saturday they would begin boarding passengers who were barred from entering the US under the executive order.

Emirates, the Dubai-based long-haul carrier, said it would board all passengers carrying valid US visas or green cards and allow them to fly to the US, including nationals from the seven countries that Trump's order had barred.

But the airline warned that "entry requirements to the US may change."