WASHINGTON (KTVU/AP) - President Trump basked in the cheers of admirers at a stop in Billings, Montana to campaign for a Republican congressional candidate Thursday, while mocking the anonymous author of Wednesday's op-ed piece who claimed to be a senior official in the administration and part of a conservative "resistance" thwarting the President's actions from inside the White House.
In the hunt for the author, denials came fast and furious from cabinet members and senior officials in the Trump administration.
National Intelligence Director Dan Coats says speculation that either he or his top deputy wrote the op-ed is "patently false. We did not."
Secretary of State Mike Pompeo spoke to reporters after a Thursday meeting in New Delhi with top Indian officials and said, "It's not mine."
Vice-President Mike Pence also denied writing the piece, addressing speculation that he might be the author because of the use of the word "lodestar" which Pence has used repeatedly.
"Anyone who would write an anonymous editorial, smearing this president who's provided extraordinary leadership to this country, should not be working for this administration, they ought to do the honorable thing and they ought to resign," said Pence.
Democrats called on senior white house staff to step forward and speak their conscience.
"If they believe that this president is not fit to serve they need to step up and let the country know," said Democratic Hawaii Senator Mazie Hirono.
Some suggest moderate conservatives have found themselves at a crossroads between supporting President Trump's policies and supporting him as a person.
In Wednesday's op-ed piece, the author said President Trump "is not moored to any discernible first principles that guide his decision making."
"Although he was elected as a Republican, the president shows little affinity for ideals long espoused by conservatives: free minds, free markets and free people. At best, he has invoked these ideals in scripted settings. At worst, he has attacked them outright," wrote the author.
The op ed author wrote, "Given the instability many witnessed, there were early whispers within the cabinet of invoking the 25th Amendment, which would start a complex process for removing the president. But no one wanted to precipitate a constitutional crisis."
"This is really unchartered territory in terms of our politics," said UC Berkeley Politics professor Eric Schickler, who notes that in the past senior officials have resigned from administrations, rather than subvert a president's actions from inside the White House, or publicly berate a president.
Schickler says the constitution's 25th amendment provides a path for the Vice-President and cabinet to join Congress in removing a president.
"I think that what we have is kind of a political crisis than a constitutional crisis," said Schickler.
"If there were an effort to invoke the 25th Amendment. I think the roughly 40% of the country that are true believers in President Trump, they wouldn't believe the process. They would see it as a kind of coup..."
Massachusetts Democratic Senator Elizabeth Warren says if senior officials believe the president is unfit, "they should stop hiding behind anonymous op-eds and leaking information to Bob Woodward" and "do what the Constitution demands they do: invoke the 25th Amendment and remove this president from office."
Former Attorney General Eric Holder says an anonymous New York Times opinion piece criticizing President Donald Trump is "alarming" but "consistent with what we have seen in previous books, in previous stories about the dysfunction of this administration."
Holder made the comments in Las Vegas Thursday while appearing with a Nevada gubernatorial candidate.
The Democrat says the focus should not be on which Trump administration official wrote the piece, but on its content.
Holder says it's "also disturbing to think that you could have people who are not elected making decisions about the way in which this country is governed."
He says Democrats need to win elections in 2018 to serve as a check on the president and Republicans need to put "country before party."
A congressional ally of President Donald Trump says he thinks Congress could investigate which senior administration official wrote an anonymous New York Times opinion piece criticizing the president.
Rep. Mark Meadows, R-N.C., says he thinks the issue is "serious from a national security standpoint." He is the chairman of a House subcommittee that oversees the president's executive office and a founder of conservative Freedom Caucus.
Meadows, chairman of the conservative House Freedom Caucus, said he disagrees with House Speaker Paul Ryan, who said earlier in the day that he doesn't know what role Congress would have in investigating the opinion piece. The anonymous author claims to be part of a "resistance" to Trump.
Meadows said that "we are looking at what is proper" to investigate but said he hasn't yet taken "concrete steps."
Associated Press contributed to this report