Sumpter, who's about to give birth to a little girl, said this film was a gift to her daughter.
"Because I got to play such a strong, independent complex woman who was actually the prize in the movie and a lot of the times in these movies, women are chasing after men and Barack had to win me over," she said.
Sawyers, who plays the commander in chief, said the director wanted him to bring more of himself and less of Obama into the role.
"I started off as a full-on impersonation," Sawyers said, laughing. "He's a 28-year-old who is just trying to get a girl."
Surprisingly, Sumpter said she and Sawyers are more excited than nervous for the Obamas to see their movie.
"We're super proud of the work we did," Sumpter said. "We really prepared and we worked really hard on this movie and it's a love story, it's a date movie and I think they'll enjoy it. I hope they'll enjoy it."
Both Sumpter, 36, and Sawyers said they hope viewers leave with a smile on their faces after seeing the film.
"And there's so many themes throughout," Sumpter said. "It's about forgiveness, it's about change, it's about seeing yourself through somebody else's eyes. But, ultimately, it's a good date movie so men can take notes and I think they'll enjoy it."
"Southside With You" opens nationwide on Friday.