It also doesn't appear that the essay revealed any classified information, which would be a crucial bar to clear before a leak investigation could be considered.
Porter, who graduated from Brigham Young University and Harvard and was a Rhodes Scholar, plays a key role in the book - he's mentioned more than 200 times - mainly for his work to deflect some of Trump's half-baked plans and coax him toward better policies.
"People who are well-respected in this administration have come out and denied it", he said. A new book says Prime Minister Narendra Modi wanted to have dinner with Donald Trump there last June.
He and the CBS late night host discussed what exactly shocked Woodward the most about the Trump White House.
It appeared to be another instance of the president versus the administration, as Trump proceeded on one track while the agencies largely moved on another.
President Trump also tweeted that Woodward's book is "a joke" and "another assault" against him.
US President Donald Trump says he'll write the real book on his presidency.More news: England 1-0 Switzerland: Danny Rose says first half performance was 'embarrassing'
"These are political statements to protect their jobs", Woodward said.
That claim aside, people inside the West Wing say the identity of the writer remains a topic of heated discussion as reports emerged that a list of possible authors had been drawn up.
"The mood in the White House, to just take the Woodward book for instance and the anonymous op-ed to start with, the president is angry and frustrated", Washington Post White House reporter Ashley Parker explained.
But on Monday, the White House reasserted its interest in studying whether any laws were broken by the explosive op-ed's author. On Monday, it was ranked as the top-selling book on Amazon.
Woodward has said he stands by the reporting in his book, which offers a harrowing portrayal of Trump's tenure, with aides seeking to curb his worst impulses, and Trump denigrating some of those who work around him, including Attorney General Jeff Sessions.
"If you look back at Woodward's past, he had the same problem with other presidents, he likes to get publicity, he sells some books", Trump said last week. In one part, Woodward writes: 'Mattis was particularly exasperated and alarmed, telling close associates that the president acted like - and had the understanding of - "a fifth- or sixth-grader"'. Both deny the statements.
The Late Show is an hour-long show, and 20 of those minutes went to Woodward and Colbert talking about the book, its contents, and even a few historical references.