At the U.S. State Department, the dissent began building soon after President Donald Trump signed an executive order late on Friday to limit immigration from seven Muslim-majority countries.
Opposition mounted through the weekend as a draft memo criticizing Trump's policy was written up in Washington and circulated by email to U.S. diplomatic posts around the world, according to multiple officials involved in the effort.
By Monday, two of the officials said they considered withdrawing their names from the document, fearing a backlash.
On Tuesday, just 12 days into Trump's presidency, the memo with some 900 signatures was delivered to the State Department policy planning office and from there to other top officials, said one source familiar with the document.
Sources said this was an unprecedented number of names on a memo sent through the department's formal "dissent channel."
The memo is just one example of the alarm and, in some cases, resistance spreading within the federal bureaucracy as Trump's administration makes sharp policy turns while ignoring some of the agencies charged with implementation, according to interviews with more than 20 current and former U.S. officials who spoke on condition of anonymity and in some cases asked that their departments not be identified.
Still fearful of recriminations, one official said some diplomats discussed whether they could qualify for professional liability insurance, which would cover legal costs in the case of disciplinary action, through the American Foreign Service Association union.
The White House did not respond to an email requesting comment.
Earlier, when the existence of the memo surfaced, White House spokesman Sean Spicer warned that anyone at the State Department who questioned Trump's immigration policies "should either get with the program, or they can go."
Elsewhere in the federal bureaucracy, officials have hastily saved scientific research and public information on climate change and other issues, fearing the new administration would strip it from their websites.
Officials have also set up alternative Twitter accounts to criticize the administration. Reuters could not verify the owners of the roughly 50 "rogue" accounts.
Other officials have begun debating whether to quit.Most of those whom Reuters interviewed said that, while the administration's policies concerned them, they are more worried that Trump might try to ignore legal and legislative restraints on presidential power.
Trump upset many by signing his controversial executive order on immigration without consulting key agencies and members of Congress.
"When they try to ram through things that have foreign policy and national security implications, it demands consultation," said a career official who worked in a part of the government charged with implementing the immigration order. "But there was no meaningful consultation, despite what they said."
A career civil servant at the Federal Communications Commission said he was considering quitting, citing a fear widespread at the agency "of being cut out of the decision-making processes."
Senator Bob Corker, chairman of the Senate Foreign Relations Committee and a Republican like Trump, said he learned about the immigration order only after the president had signed it.
Corker said he talked with White House representatives on Sunday and believed they had gotten the message on the need for inter-agency coordination.
"I would find it hard to believe that they on Tuesday don't understand that what they did on Friday could have been done in a much better way," he said.
Most new presidents, particularly Republicans, who favor limited government, have tussles with the federal bureaucracy.
President Ronald Reagan fired 11,000 air traffic controllers, all federal employees, in 1981, early in his tenure, after they ignored his order to return to work.
But Philip Wallach, a senior fellow at the Brookings Institution think tank, said Trump's apparent hostility to those who must implement his policies was in a different league.
"There certainly is something about Trump's chip-on-the-shoulder attitude that makes it seem like he's itching for a potential long-term fight with the bureaucracy, rather than something he works to develop a smooth relationship with," he said.
To succeed with his economic reform agenda, Trump will need federal agencies, Wallach said. "That's going to require a lot of affirmative government work, not just smashing things up."
Several government managers said they have advised their employees not to react so early in Trump's presidency.
"Some of the things Trump is doing are foolish and make no sense from a management perspective," said a career State Department official who supervises scores of civil servants.
"But I've told my folks to be professional and stay calm – don't panic," the official said. "What else can I tell them? Someone needs to be an adult. Otherwise, we'd have chaos."
In a farewell speech to about 100 State Department officials on Tuesday, Thomas Countryman, the acting undersecretary of state for arms control and international security, called on colleagues to stay despite their concerns.
"We still have a duty - you have a duty - to stay and give your best professional guidance, with loyalty, to the new administration," he said. "Because a foreign policy without professionals is - by definition - an amateur foreign policy. You will help to frame and make the choices."
(Additional reporting by John Walcott, Jonathan Landay, Matt Spetalnick, David Rohde, John Shiffman, Roberta Rampton, Valerie Volcovici, Arshad Mohammad, Patricia Zengerle, Mark Hosenball, Emily Stephenson and Daniel Weissner; Editing by John Walcott, Kieran Murray and Lisa Von Ahn)