Credit: NBC © NBC Universal, Inc Photo: Ivy Lynn and Karen Cartwright in the Smash Premiere

There’s no doubt that Ivy Lynn (Megan Hilty) would make an excellent Marilyn Monroe in Smash’s fictional Broadway musical. With her platinum blonde hair and sexy pin-up figure — physically, she’s the perfect match.

Then there’s Karen Cartwright (Katharine McPhee). The doe-eyed Kansas girl looks much less like Marilyn than her competition, and that “light” [read: practically blank] resume would give casting directors cause for concern. But Karen just has a spark about her: a sense of life and energy you just can’t fake.

So why not toss on a blonde wig and sing “Happy Birthday, Mr. President” a few more times... Is that really all Karen needs in order to take Broadway by storm? Or does the role belong to none other than Ivy Lynn?