'You have no idea': Ex-aide told whistleblower his actions drove Trump nuts

Among those who have faced President Donald Trump's revenge campaign is Miles Taylor, the former Homeland Security chief of staff who penned an anonymous column and book.

Taylor spoke to MSNBC's Nicolle Wallace on Tuesday's episode of "Deadline White House," where he stated that he was told Trump had an obsession with him during the first term — and it's clearly continued for the past seven years.

Wallace asked him what his best guess was that prompted Trump to be so angry with him.