(CNN) Former White House chief of staff John Kelly issued an on-the-record statement Friday night lambasting President Donald Trump for not helping with the transition to a Biden administration.
"The delay in transitioning is an increasing national security and health crisis. It costs the current administration nothing to start to brief Mr. Biden, Ms. Harris, the new chief-of-staff, and ALL identified cabinet members and senior staff," Kelly wrote in a rare public rebuke of his former boss.
Kelly added that "the downside to not doing so could be catastrophic to our people regardless of who they voted for."
READ: John Kelly's statement on Trump not helping with the transition to a Biden administration
"The current administration does not have to concede, but it should do the right thing just in case the Constitutional system declares they lost. It is not about the GOP or the Democrat Party. It is not about the president or about Mr. Biden. It is about America and what is best for our people," Kelly wrote. "Mr. Trump should order the transition process begin immediately. It is the right and moral thing to do."
Politico was first to report on Kelly's thoughts about Trump's refusal to allow President-elect Joe Biden to begin working with federal agencies on the transition.
Republican lawmakers have begun backing the idea of Biden's transition team receiving the same intelligence briefings that Trump receives, especially after Oklahoma Sen. James Lankford, a Republican, backed the idea earlier this week.
In making his argument, Lankford noted that after the 9/11 terrorist attacks, the bipartisan committee that investigated them found that the compressed time frame for the transition after the contested 2000 election may have contributed to the lack of preparedness for the attack.
In its report after the attacks, the commission said that the dispute over the election and the "36-day legal fight" that followed "cut in half the normal transition period." The loss of time, the commission said, "hampered the new administration in identifying, recruiting, clearing, and obtaining Senate confirmation of key appointees," diminishing US preparedness before the terrorist attacks.
Trump spoke in public on Friday for the first time since a brief speech making baseless claims about the election last week and did not acknowledge that he had lost the presidential race. CNN on Friday projected Biden will win Georgia and Trump will win North Carolina, the last two states that had yet to be called, bringing the final total of electoral votes to 306-232 in favor of Biden.
Kelly, who left the White House under contentious circumstances in January 2019, has occasionally voiced criticisms of the Trump administration since leaving his post. He has told friends that Trump "is the most flawed person" he's ever known, CNN reported last month.
"The depths of his dishonesty is just astounding to me. The dishonesty, the transactional nature of every relationship, though it's more pathetic than anything else. He is the most flawed person I have ever met in my life," the retired Marine general has told friends, CNN learned.
In June, in the wake of George Floyd's killing at the hands of Minneapolis police and Trump's response to the subsequent protests and calls for racial justice, Kelly said he agreed with former Secretary of Defense Gen. Jim Mattis' stark warning that Trump is "the first president in my lifetime who does not try to unite the American people."
Kelly said he would have cautioned Trump against the idea of using law enforcement to clear Lafayette Square of protesters ahead of the President's now infamous photo in front of a nearby church.
Kelly also defended retired Army Lt. Col. Alexander Vindman for raising concerns about the President's call with Ukrainian President Volodymyr Zelensky -- the call at the heart of the President's impeachment. And Kelly has said he believes former White House national security adviser John Bolton's allegation that Trump conditioned US security aid to Ukraine on an investigation into political rivals.
This story has been updated with additional information.