Former intelligence officials, some of whom once provided similar briefings, told CNN that the qualities that have propelled Trump to the top of the Republican ticket -- a swaggering stream-of-consciousness speaking style peppered with off-the-cuff zingers -- are exactly the traits raising alarm. They worry that the New York real-estate mogul may not have the temperament or experience to handle sensitive security information with discretion.
"The real concern that people are expressing about Mr. Trump is that Mr. Trump has never been in any position, that is known, that has exposed him to top-secret intelligence," said David Priess, a former CIA officer, pointing to comments in the media from the intelligence sector. The Republican front-runner also isn't used to "compartmentalizing information he has heard that should not be spoken of outside of a certain room," Priess said.
But Priess and other former officials say the initial briefings presidential nominees get from career intelligence officers, while classified, won't include the most sensitive details contained in the President's Daily Briefing. That summary of the world's crises -- once dubbed the "pickle" and now known as the PDB -- has its roots in World War II and has been evolving ever since.
On Wednesday, Director of National Intelligence James Clapper stressed the intelligence community's impartiality at a Bipartisan Policy Center event in Washington, D.C., when asked how briefers might try to shape Trump's world views, particularly his highly criticized December proposal for a "total and complete shutdown of Muslims entering the United States."
"The question implies that we have a separate message for each candidate and we do not," Clapper said.
The briefings are "not designed to shape anybody's world view," Clapper said. "We just brief as we normally would, each of them, and they have to be exactly the same and we will do that again with this campaign once the candidates are known officially for each party."
In a political season where Democratic front-runner Hillary Clinton also faces scrutiny over her handling of sensitive material when she was secretary of state, current and former intelligence officials say that the traditions that have grown up around the briefing provide some protections and stringently emphasize an even-handed fairness for candidates on both sides of the aisle.
"There's an understandable wariness about Donald Trump," said Bruce Riedel, another former CIA officer who now heads the Brookings Institutions' Intelligence Project. He noted that Trump "has no record dealing with classified information, so it's an unknown, but whoever does the briefings is going to be conscious of that and that they need to be careful."
"I think the agency will treat him like any other candidate," Riedel said.
Asked about the concerns some are airing about Trump's ability to handle classified information, his spokeswoman Hope Hicks told CNN, "we will absolutely have no problem keeping it private. Nobody can hold information better than Mr. Trump."
Last month, Clapper told reporters at a Christian Science Monitor breakfast that a plan and a team have already been established for briefing the candidates after they've been chosen at their parties' conventions. That will be lead by a career officer and not a political appointee, Clapper made clear.
The team's job, Clapper said at the breakfast, is to "ensure that everybody gets the same information and that we do comply with the needs to protect sources and methods and comply with security rules."
Great care is taken to ensure there's no favoritism. Both candidates get the exact same briefing. If one asks a question and gets a response, that question and response are shared with the other candidate, according to Priess, whose history of the PDB, called "The President's Book of Secrets," came out this year. "These are not partisan, there is no favoritism," he said. "Great pains are taken."
Riedel said also that "a lot of care is given to ensuring a candidate does not get a briefing that he or she unintentionally -- or worse, intentionally -- could use to campaign advantage."
President John F. Kennedy wasn't told about the plan for the Bay of Pigs until he was elected, for example, even though it was already in the works. Today's candidates aren't likely to hear about drones or National Security Agency collection capabilities, Riedel said.
"I'd use the word vanilla" to describe the information given to the candidates, said Riedel, who briefed President George H.W. Bush. They are broad overviews, with "a lot of 'here's what the situation in Syria is, here's how ISIS is doing.' "
Naming the leader of ISIS, he added, "They're not going to get 'here's where Abu Bakr Baghdadi sleeps at night and here's what we're planning on doing about him.' "
And enormous emphasis is placed on the need to treat the information with care, according to those who have conducted briefings.
Traditionally, the post-convention briefings take place at a time and place that suits the candidate.
"We normally will accommodate their needs through a local secure facility," Clapper said.
The candidates can ask for more than one briefing, but that doesn't often happen, Priess said.
They are "busy trying to shake as many hands as possible," noted Priess, who even recalled one instance in which a candidate turned the initial briefing down.
During the 1984 presidential race, Democratic nominee Walter Mondale declined a briefing. He'd been vice president for four years and had served on the Senate Intelligence committee and was no stranger to intel matters. Years later, he offered another reason for declining, Priess recounted, saying it was clear he was going to lose to Ronald Reagan and didn't see the point.
In one instance, a candidate got a briefing before getting his party's nod. In 1976, Democratic candidate Jimmy Carter, aware of his shortfalls in foreign policy, asked Republican President Gerald Ford if he could be briefed before the convention. Ford sent his CIA director, George H.W. Bush, down to Carter's suburban Georgia house in July.
Richard Lehman, the CIA officer who had developed the President's Daily Briefing, was there and recalled years later in a public interview that "it was hotter than hell, and in order to be able to hear you had to shut off the air conditioner."
For five hours, they briefed Carter, who "sat without getting up and very intent, totally concentrating and taking it all in."
The impetus for candidate briefings had come decades earlier, when Harry Truman assumed the country's highest office after President Franklin Roosevelt suddenly died in 1945, Priess notes in his book.
Truman had been vice president but had had no idea that the Manhattan Project to build an atomic bomb was in the works. He decided that his successors should never be put in that position and ordered that intelligence briefings should be given to both the major party candidates in an election.