Obama and Michelle on-screen adaptation lead cast

Parker Sawyers will depict the President in the film 'Southside With You'. Photo / AP via The Telegraph

When Michelle Obama was asked who might play her husband on the big screen her thoughts turned immediately to two of America's best-known black actors.

"Denzel Washington and Will Smith," the First Lady mused. "Will's got those ears, though, which might give him an edge."

But the first major onscreen portrayal of Barack Obama has instead fallen to Parker Sawyers, a newcomer American actor who lives in West London with his wife and young children.

The 31-year-old will play Mr Obama in Southside With You, a romantic film based on the true story of the President's first date with his future wife Michelle in Chicago in 1989. The entire movie is set over the course of a single day as the pair flirt and match their wits in between stops at an art museum, a cinema and an ice cream shop.

A young Barrack Obama with wife Michelle. Photo / The Telegraph

While other films have been made already about Mr Obama's presidency, they have have relied on spliced news footage or an off screen voice for the man himself, so Mr Parsons will be the first to actually play Barack Obama.

"It's an honour," Mr Sawyers told The Telegraph from his home in Parsons Green. "You just try to stay calm but then people ask: do you think he'll watch it? And I'm like, oh man he will watch it, won't he?"

Mr Sawyers, who worked for Mitch Daniels, the Republican governor of Indiana before moving into acting, looks more like Mr Obama then either Denzel Washington or Will Smith. And he did a convincing impression of Mr Obama's distinct voice over the phone as he imagined a phone call with the President.

While the world knows Barack Obama as a man in his forties and fifties - with a wife and children and the responsibilities of high office - Mr Sawyers has had to figure out how to play Barack Obama the self-confident 28-year-old law student.

Much of the character comes from the script, Mr Sawyers said, but he has gathered a few video clips of Mr Obama from his time at Harvard to get a sense of his younger days.

The film sticks reasonably faithfully to the true story of how the Obamas met at the Sidley Austin law firm in Chicago, where the more senior Mrs Obama was assigned to mentor the young Barack during a summer job.

In Mr Obama's telling of their love story, he pestered her to go out with and she finally agreed to lunch at an art museum and then to see Do the Right Thing, a Spike Lee film about racial tension in New York.

"He was trying to show me his sophisticated side by selecting an independent filmmaker," Mrs Obama said in a video to mark the 25th anniversary of the film.

They ended up at a Baskin Robbins ice cream shop where Mr Obama made his move. "I kissed her, and it tasted like chocolate," he later said.

Slightly bizarrely, a plaque now marks the spot of the first kiss at the corner of Dorchester Avenue and 53rd Street.

Mr Sawyers has lived in London for much of the Obama presidency but his mother, a former Republican city official in Indianapolis, has met the President and is "freaking out" at her son's latest role. "The room disappears when you shake his hand," was how she described her brief meeting with Mr Obama.

People often remarked that Mr Sawyers looks like Mr Obama and while working as a model in Chicago he started to deliberately wear a baseball cap to discourage the comparisons.

He arrived on the set of Zero Dark Thirty, where he had a small role as a CIA interrogator, with a scruffy beard but when he shaved it off director Kathryn Bigelow was struck by the similarities. Oliver Stone also gently made fun of Mr Sawyers during shooting for an upcoming movie about Edward Snowden, where he plays an American intelligence official.

Mr Sawyers has met Reggie Brown, one of the most prominent Obama impersonators and said he was a fan of Keegan Key, who plays Mr Obama's "anger interpreter" Luther. The comic and the President appeared together at this years' White House Correspondents' Dinner.

Southside With You will be the first leading role for a man who came to late to acting. "I had never acted I had never done a school play at all," he said.

He was working as a musician and taking his daughter to a London park when he met an actor whose agent represented people with American accents and a month later was in his first role as a Norwegian cross dresser for the television show Lilyhammer.

While the upcoming film will be shot in Chicago over the summer, Mr Sawyers says London is now home for himself and his Lithuanian wife and internationally-oriented children.