When vice president Harry Truman received a telephone call summoning him to the White House he knew but not want to admit to himself why he had been called. After walking alone through the capitol building and driving to the White House, where he had only once been as vice president for lunch with Roosevelt, Truman received the news from Eleanor Roosevelt that the president was dead. Soon Truman would learn for the first time of the Manhattan Project, a secret Roosevelt had kept from him.

Truman never forgot the experience of jumping into the most important decision of his life with absolutely no preparation. He was determined to never let it happen to future presidents. Beginning in 1952 Truman authorized intelligence briefings for Republican candidate Dwight Eisenhower, even though Truman was outraged at Eisenhower’s betrayal of General George Marshall under fire from Senator Joseph McCarthy. Eisenhower ordered the CIA to brief Senator John Kennedy, omitting the buildup to the Bay of Pigs invasion of Cuba a project Kennedy would not learn of until after his inaugural. Lyndon Johnson gave candidates Richard Nixon and Spiro Agnew a CIA briefing at LBJ’s Texas ranch.

Gerald Ford allowed Jimmy Carter access to national security briefings delivered by the CIA director George H.W. Bush. Carter extended the courtesy to candidate Ronald Reagan, who seemed uninterested, and to third-party candidate John Anderson. The tradition continued for candidates Barack Obama and John McCain. Obama returned the favor to Mitt Romney.

Although the tradition of president candidate briefing has an uneven history it has a kind of a feel-good aspect to it, a small example of setting aside partisan bickering for the good of the country, a tiny redemptive act in a toxic political landscape. But it is important to stress that it is only a tradition or a precedent. It is in no way whatever a law, a rule or a mandate.

Which brings us to the happy year of 2016, It is the year when one of the once great political parties of America was taken over by the most unqualified, irresponsible, reckless, uninformed and dangerous people in history: Donald J. Trump.

In his rambling, incoherent string of insults, blowhard bragging and conspiracy theories that pass for speeches Trump has repeatedly demonstrated his inability to distinguish facts from fantasies, policies from prejudice and  truth from lies.

Now imagine arming this very unfunny clown after a national security briefing. In one decibel inflated speech Trump could reveal more and do more harm to the country than Chelsea Manning or Edward Snowden ever imagined. It is simply a terrifying prospect, like giving an arsonist a gallon of gasoline and a book of matches.

It is incumbent upon the Obama administration to put the national interest over a tradition of courtesy. Put a stop to this before the damage can happen. Deny Donald Trump access to the national security information that he will abuse if given the opportunity. There will be some howling from Congress about unfair treatment but it will pass. If the Republican Party can purge itself of this infection and reestablish itself as a legitimate political party in 2020 the briefings can and should resume.   Some precedents need to be broken. Break this one.