Paul assailed Brennan in a Fox News interview as "completely unhinged" and a "Trump hater" and in a series of tweets on July 23, said he planned to meet with Trump at the White House and tell him that "John Brennan and other partisans should have their security clearances revoked".
Mr Brennan's loss of a security clearance was an unprecedented act of retribution against a vocal critic and politicises the U.S. government's security clearance process.
Brennan's thesaurus-heavy Tweets and self-righteous grandstanding have made him a hero to the anti-Trump #resistance.
Clapper, reacting on CNN, said he didn't plan to stop speaking out about the Trump administration.
Also on the list: fired FBI agent Peter Strzok, who was removed from the Russian Federation investigation over anti-Trump text messages; former FBI lawyer Lisa Page, with whom Mr Strzok exchanged messages; and senior U.S. justice department official Bruce Ohr, whom the president recently accused on Twitter of "helping disgraced Christopher Steele 'find dirt on Trump'".
Paul told reporters this week that Russian officials refused to acknowledge interfering in the 2016 presidential campaign and he said the USA should stop expecting the country to confess.
Sen. Mark Warner, the top Democrat on the Senate Intelligence Committee, warned a "dangerous precedent" was being set.
In an interview with the Wall Street Journal on Wednesday, Trump said he had wanted to announce the decision last week but his schedule was too "hectic".
Former top government officials like Brennan traditionally have retained their security clearances so they can advise their successors as well as continue to work in high-level foreign affairs positions. He is saying he is punishing people who were involved in that, which at the very least would seem to create a chilling effect for other would-be critics. "I will not relent", he said.
The New York Times had mentioned that "t$3 wo of the targets Ms. Sanders cited, James B. Comey, who was sacked by Mr. Trump as F.B.I. director in 2017, and Andrew G. McCabe, who was dismissed in March as deputy director of the F.B.I., no longer have security clearances".
White House Press Secretary Sarah Huckabee Sanders denied that Trump was retaliating for Brennan's criticism. "Mr Brennan has a history that calls into question his objectivity and credibility".
"My principles are worth far more than clearances", he added".
The President said he has also begun to review the more general question of the access to classified information by government officials and is evaluating action against former director of national intelligence James Clapper, former Federal Bureau of Investigation director James Comey, former head of the NSA Michael Hayden, former acting attorney general Sally Yates and former president Barack Obama's NSA Susan Rice and others. I think he finally gave Brennan the hook for no better reason than that Brennan shot his mouth off about how bad Trump is one too many times and POTUS chose to pull the trigger.
Unless one understands and remembers this, it is understandably hard to believe that the very top US law enforcement and intelligence officials did what documentary evidence has now demonstrated they did.
Trump - who plainly feels constrained from trying to remove Mueller - can not do anything about the Mueller investigation except tweet wildly about it and threaten not to sit for an interview.
The current administration has questioned the loyalties of such officials, viewing their comments as attacks against the president, especially those focusing on the intelligence findings that Russian Federation intervened in the 2016 election won by Trump.