Nice Guys Finish First: John Gallagher Jr. on 'The Newsroom,' 'Short Term 12'

John Gallagher Jr. in "The Newsroom."

The Tony-winning actor, who portrays "heartbroken" producer Jim on Aaron Sorkin's HBO series, opens up about his latest film role as a saintly supervisor at a foster-care facility in "Short Term 12."

Tell any avid Newsroom-watcher that you're interviewing John Gallagher Jr. and expect to hear varied reactions of the following: "I love that guy!" Or: "He seems cool!" Or, if it's your mom, "Is he single?"

On-screen, the 29-year-old star -- who portrays love-lorn, hyper-competent, eternally-rumpled senior producer Jim Harper on the HBO series -- is the slightly-hipster guy next door, pining after fellow News Night staffer Maggie (Alison Pill) while helping run the chaotic ACN office with unflappable professionalism. The character has been compared with another TV Jim -- Halpert -- from The Office, in terms of every-dude likability, secret co-worker crushes and floppy hairstyles. (See also: "the sheepish boy shrug," as observed by the amusingly accurate Tumblr "Harper or Halpert?")

On a recent sweltering afternoon in New York City, escaping the heat in the airy, artsy "private workplace collective" Neuehouse, the polite, good-natured Gallagher Jr. -- not to be confused with Jim Harper, Mom -- has traded his business-casual Newsroom wardrobe for off-duty actor attire (jeans and a T-shirt) to talk with The Hollywood Reporter about the Aaron Sorkin-penned HBO series and his latest big-screen venture, Short Term 12

"He’s heartbroken," Gallagher Jr. said of his small-screen alter ego, who left the ACN newsroom at the start of season two to travel with the Mitt Romney campaign -- and thereby avoid the presence of Maggie after she resumed dating another producer, Don (Thomas Sadoski), even though she confessed her feelings for Jim ... oh, it's all a big mess.

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"He's gonna grow up a little bit" on the road "and learn a little bit more about what he wants and who he wants to be," explained Gallagher Jr., adding: "I think a serious relationship is something that he’s never entertained before in his life. It’s been work, work, work, work, work all through his teens and all through his early 20s, and now he’s reaching a point in his life where I think he's starting to think about his future and ‘Do I want to settle down? Do I want to be able to have a meaningful, committed relationship?’"

A Don-less Maggie, meanwhile, gets permission to embark on an ill-fated journalistic excursion to Africa that leaves her traumatized; on Sunday's episode, she is shown recalling the trip and the violent incident that leads the frazzled rookie reporter to chop off her long blonde hair and dye it a bright Miranda Hobbes-shade of red. (Read THR's extra-spoiler-y recap of the episode here.)

"[Jim] and Maggie are both on these planes, these trajectories, where they're gonna take some time off, some time away from each other to maybe do their own growing and maturing – to, hopefully, ideally, in my mind, to be able to come back and be better versions of each other. For each other," noted Gallagher Jr., endorsing an inevitable Jim-Maggie coupling.

The Broadway veteran, who won a 2007 Tony Award for his role as anxious Moritz Stiefel in the original production of the musical Spring Awakening, balances the premium-cable drama with a big-screen role in the acclaimed indie Short Term 12, which he filmed while on hiatus last September.

The drama, which won the Narrative Audience Award at this year's SXSW Film Festival and is slated for release on Aug. 23, stars Gallagher Jr. and Brie Larson as Mason and Grace, two romantically-involved supervisors at a foster-care facility for at-risk teens. While Grace is tough-minded and intense, grappling with the effects of childhood abuse, Mason -- a near-saint whose glass is always half-full -- provides unconditional love and support.

VIDEO: 'Short Term 12 Trailer': Take a Look at the Breakout Hit of SXSW

“It’s kind of a brave role to write nowadays because I feel like the cool thing to do is write people that are really in their head and kind of selfish," he said of Mason, created by Short Term writer-director Destin Daniel Cretton.

"There’s a lot of guy roles that you see now that are just ‘unapologetically do what they want,' and there’s something cool about someone who’s ironic or sarcastic, and I think he’s such a heart-on-his-sleeve kind of character in a way that is refreshing," he added.

Gallagher Jr., who landed the part following a Skype conversation with Cretton, has not yet lined up another movie gig, but would "like to do another play sooner rather than later." Still, after a two-year hiatus from the stage, he admitted to having doubts, thinking aloud: "Can I still do it?"

“Luckily doing an Aaron Sorkin show, sometimes there’s so much dialogue that it feels like you’re doing a play."

Twitter: @ErinLCarlson