To answer the most obvious question first: No, you won't have any trouble at all buying Bill Murray as President Franklin Delano Roosevelt in Hyde Park on Hudson, a seriocomic portrait of the POTUS as an aging horndog.

Granted, Murray doesn't do much more than flatten his vowels here and there — and occasionally adjust his pince-nez while a cigarette holder dangles rakishly from his lips — to hard-sell the verisimilitude. But never mind: Not unlike Frank Langella in Frost/Nixon, he credibly and compellingly conveys the essence — or at least what most of us have come to believe is the essence — of the icon he's portraying here.

A Frost/Nixon comparison also is applicable to the central conceit at the heart of this handsomely produced period drama directed by Roger Michell (Notting Hill, Changing Lanes) and written by Richard Nelson.

Peter Morgan's screenplay (based on his own stage play) for Ron Howard's underrated 2008 film pivoted on the thought-provoking, dramatically satisfying supposition that both British TV personality David Frost (Michael Sheen) and disgraced former president Richard Nixon (Langella) approached their legendary TV interviews with similarly self-serving goals of image enhancement.

In Hyde Park on Hudson, we have a cheerily paternal FDR playing host to an anxious young King George VI (Samuel West) — and his wife, the Queen Consort Elizabeth (Olivia Colman) — in June 1939 at the upstate New York enclave that gives the movie its title. It's a very special occasion — and not just because no British royals had ever previously visited America.

King George dearly hopes to bolster U.S. support for the United Kingdom during what appears to be an inevitable war with Germany. (Sure enough, three months later, Germany invaded Poland.) At first, however, he feels awkward in his dealings with FDR — and self-conscious about his stutter. (Evidently, Geoffrey Rush — er, I mean, Lionel Logue — hasn't yet completed the speech therapy sessions detailed in The King’s Speech.)

And while Elizabeth means well, she doesn't do much to boost her husband's confidence by repeatedly chiding him for his stammer and comparing him, unfavorably, to his more charismatic brother, who might still be King of England if he hadn't fallen in love.

The best scenes in Hyde Park on Hudson are those that focus on the untested king and the fatherly president — that show how acutely aware they are of the burdens they bear and the images they must maintain — while these two very public figures share confidences about their private lives and inner doubts.

To be sure, there's something perhaps a tad too neat about the ice-breaking moment when each man acknowledges his handicap. ("This goddamn stutter!" "This goddamn polio!") And, yes, just as the real David Frost wasn't quite the journalistic lightweight that Morgan depicts in his drama, the real King George wasn't that much younger than FDR in 1939. (The king was 43, going on 44, while the president was 57.)

But, again, never mind: Hyde Park on Hudson is fascinating and often quite funny as it examines how a unique relationship between men solidified a "special relationship" between countries. And it subtly but effectively amuses by noting the irony that just as one man finally earns the respect of the most important woman in his life, the other — FDR — continues to muddle through complicated relationships with the women in his own orbit.

Unfortunately, most of Hyde Park on Hudson isn't about the bonding of world leaders, but instead about, well, those women in FDR's life.

Specifically, the movie devotes the bulk of its running time to the relationship between FDR and Margaret Suckley (Laura Linney), a distant cousin who becomes the president's very, very close acquaintance shortly before the royal visit.

Even more specifically, the movie is intended primarily as Margaret's story: How she fell under FDR's spell and how she was hurt when she discovered how many other women — in addition to FDR’s wife, Eleanor, played by Olivia Williams — had enjoyed (or were still enjoying) the same, ahem, easy access to the president.

"My husband," Eleanor pointedly remarks, "lives for the adoring eyes of young women."

Remember my remark about "aging horndog" in the first paragraph? That really wasn't much of an exaggeration.

Hell, Margaret — a real-life figure whose private journals and diaries inspired Richard Nelson's script — even serves as the movie's narrator, despite the fact that she's nowhere around when key events occur. (Sure, maybe FDR told her after the fact about his conversations with George. But what about George's private conversations with Elizabeth?)

With all due respect to Laura Linney — a fine actress who is, as usual, splendid — Margaret's story, while not uninteresting, really isn't interesting enough to lay just claim to as much time as it gets in Hyde Park on Hudson. Maybe I'll watch the movie again someday on DVD. When I do, however, I suspect I'll be doing quite a bit of fast-forwarding.