The pivotal chapter on the 1960 Democratic Convention in The Passage of Power, the just-published and justly heralded fourth volume of Robert Caro’s Lyndon Johnson saga, is entitled “The Back Stairs.” The little-used staircase in question was in the Biltmore Hotel in Los Angeles, and it provided a stealthy way to scamper from John Kennedy’s suite (Room 9333) or Robert Kennedy’s (Room 8315) to Lyndon Johnson’s encampment (Room 7333) during the vice-presidential negotiations.

The reason for the subterfuge, as Caro recounts: “That morning what one reporter referred to as the ‘pushy, sweaty mass’ of the press—newspaper and magazine reporters and photographers, television cameras, cameramen and correspondents—was clustered around the elevator’s doors.” In short, every time that either of the Kennedys or LBJ stepped out of his hotel suite and strode towards the elevator, he walked into an impromptu press conference. Sometimes individual reporters got lucky: the morning after Kennedy was nominated, he gave a brief interview to Marvin Miles of the Los Angeles Times, who had been camped outside Johnson’s door during JFK’s meeting with his would-be vice president.

A half-century later, this image of the free-range press pack roaming the corridors of the convention hotel provides plenty of reason to envy political reporters from Teddy White’s era. (Other reasons: their sheer talent; the titanic political figures they covered; and the vibrant newspapers and magazines for which they worked.) But the differences in press access to serious presidential contenders over even the past 25 years are nearly as stark. Traveling with Bill Clinton in 1992 for Time magazine, I picked up a strong sense of the candidate from his stray comments and night-owl ramblings aboard his campaign plane. Logging many hours aloft with George W. Bush and Al Gore in 2000 as a columnist for USA Today, I picked up a strong sense of the obfuscations of press handlers Karen Hughes (Bush) and Chris Lehane (Gore).

I did write a book, One-Car Caravan, about the insights I gained from early travels with the 2004 Democratic contenders. (And no, it didn’t protect me from being gulled by John Edwards). But such a book would have been impossible in 2008, since Hillary Clinton and Barack Obama were swathed in bubble wrap long before they declared their candidacies.

As for this time around—well, good luck, unless you were still covering Newt Gingrich until he finally, officially, dropped out of the race on Wednesday. While reporters have had occasional off-the-record moments with Mitt Romney over the years, access is usually allocated with an eye-dropper and, until last week, the de facto GOP nominee had gone more than a month without holding a press conference.

That image of a walled-off (as well as a Waldorf) modern-day candidate was recently underscored by Ashley Parker, the New York Times reporter with the Romney portfolio. In a commentary for last Sunday’s paper, Parker wrote that squabbles with the campaign “over charter plane seating and access to the candidate became so heated that flight attendants walked down the aisle before noon, passing out red wine.” But for reporters eager to get close enough to get a glimpse of that mythical creature known as the Real Romney, the primary campaign will undoubtedly be remembered as the good old days. As Parker makes clear, the growing campaign and media entourages traveling with Romney in the months ahead guarantee that “as the bubble gets bigger, it also gets smaller.” With Obama sequestered from the press in a way that has long been typical of incumbent presidents running for reelection (see Nixon, Richard), we are about to witness two of the most hermetically sealed presidential campaigns in American history.

How much does this matter? The journalistic importance of access to the presidential candidates has been debated since the 2000 election and the subsequent post-Iraq sense that the campaign press corps was too smitten with Bush’s personality and too forgiving of his policy gaps. As a writer with his share of regrets about the Bush-Gore campaign, I unequivocally agree that a candidate’s fraternity-party charms are much less of a predictor of his presidency than his governing record, his ideological orientation, and that amorphous, but important, quality called character.

That said, I still passionately believe that studying a would-be president in a variety of settings, especially answering questions from voters and reporters, is better than only seeing him behind a podium reading a staff-written speech off a teleprompter. Had John McCain—with his trademark rolling press conferences aboard his campaign bus—beaten Bush for the 2000 GOP nomination, maybe we would have returned to an era when Kennedy-esque give-and-take with the press corps was the norm. Instead, we have gone from the frozen-out Bush administration to the chilly Obama White House, in which presidential press conferences are rare—but, at least, New York Times columnists are revered.

The latest Caro volume, although it does not address this question directly, makes a strong case for the enduring value of journalistic access to political leaders. Some of the best anecdotes and shrewdest insights about Johnson come from the reporters who covered him. (In fairness, naysayers might note that many of these stories were reserved for the post-presidency LBJ oral histories or were buried in the voluminous files that Time correspondents sent to the newsmagazine’s writers in New York and never published.) And those insights undoubtedly came, in part, from the proximity reporters had to Johnson and other leading political figures of his era. After a campaign trip to Oklahoma in his quest for the Democratic nomination in June 1960, LBJ offered Chicago Daily News correspondent Peter Lisagor a ride back to Washington on his personal plane. During the entire flight, Johnson ranted about Kennedy, calling him a “scrawny little fellow with rickets,” among other epithets. As Caro goes on to write, “There were other flights with Lyndon Johnson, jacket and tie off, sitting beside other reporters pouring out his feelings about ‘the boy.’”

Somehow I do not think that level of raw emotion and naked ambition is what the rare privileged reporters who interview Romney or Obama these days get from the encounters.

What The Passage of Power defined for me is the biggest riddle about 21st century political journalism: Why, in an age of Twitter and iPhone cameras, do we know less about the inner thoughts of the men running for president than we did when reporters hit the campaign trail equipped only with their Olivetti portable typewriters and pockets filled with dimes for the pay phones?

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Walter Shapiro just chronicled his ninth presidential campaign. He writes the “Character Sketch” political column for Yahoo News. Follow him on Twitter @WalterShapiroPD.