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.