Here's a tip from former House speaker Tip O'Neill: "All politics are local." Even the national Watergate scandal started off as local news.
In the context of All the President's Men, Harry Rosenfeld is Ben Bradlee, Lite. Rosenfeld is the local news editor who originally assigns Woodward to the story, before it becomes a national sensation. Early in the film, he's set up as a mentor figure, doling out bon mots (like a bon-bon but not as delicious):
ROSENFELD: I'm not interested in what you think is obvious. I'm interested in what you know.
He also isn't as harsh a critic as Bradlee, because local news doesn't have the same high stakes as national news. And once the story becomes national, Rosenfeld practically disappears from the movie. We think he'd be fine with that. In real life, Rosenfeld retired from the Post to head a local paper in Albany, New York. After all, he's a local boy at heart. (Source)