Pulitzer-prize winning journalist and biographer David Maraniss has dug up love letters and journal entries from President Barack Obama's ex-girlfriends to get an idea of what the president was like during his largely unknown time in New York City in his early 20s.

Vanity Fair published an excerpt of Barack Obama: The Story -- to be published June 19 -- that focuses on his relationships with Alex McNear and Genevieve Cook after graduating Columbia University. Through his letters with McNear in the summer of 1982 and Cook's journal entries from 1983-5, his ex-girlfriends describe an intelligent man who struggled a lot with his identity and made a conscious effort to define himself.

Maraniss, who won a Pulitzer for his Washington Post stories on Bill Clinton during his 1992 campaign, told Vanity Fair the book focuses on Obama's search for home and identity and ends on the day he heads off to Harvard Law School because that is when I see one story ending and another beginning.

Below are some of the most interesting revelations about the President's personality and time in New York from the excerpt, which Vanity Fair titles Becoming Obama.

  • On his own in New York, Obama experimented with his literary voice.

He writes this in a letter to Alex McNear, a girl from California he had a short-lived,  long-distance relationship with, when he was 20: Moments trip gently along over here. Snow caps the bushes in unexpected ways, birds shoot and spin like balls of sound. My feet hum over the dry sidewalks. A storm smoothes the sky, impounding the city lights, returning to us a dull yellow glow. I run every other day at the small indoor track [at Columbia] which slants slightly upward like a plate; I stretch long and slow, twist and shake, the fatigue, the inertia finding home in different parts of the body. I check the time and growl-aargh!-and tumble onto the wheel.

  • Like a typical recent grad in his early 20s, Obama was dissatisfied with his first jobs.

He started as a researcher at an organization based in Midtown Manhattan called Business International, which aimed to advance profitable corporate and economic growth in socially desirable ways. Unhappy with the work, he quit a year later and got a job for little more than half the salary organizing for a nonprofit called the New York Public Interest Research Group. He found that job depressing, which captured his mood much of that winter and early spring of 1985, Maraniss wrote. It wasn't until he left New York for Chicago to be a community organizer did he feel like he found his calling.

  • Obama liked relaxing with then-girlfriend Genevieve Cook and doing the New York Times Crossword puzzle on Sundays.

On Cook's time with Obama on the weekends during the winter of 1984: She remembered how on Sundays Obama would lounge around, drinking coffee and solving the New York Times crossword puzzle, bare-chested, wearing a blue and white sarong, Maraniss wrote. In her journal, Genevieve described: I open the door, that Barack keeps closed, to his room, and enter into a warm, private space pervaded by a mixture of smells that so strongly speak of his presence, his liveliness, his habits - running sweat, Brut spray deodorant, smoking, eating raisins, sleeping, breathing.

  • Some excerpts from his memoir, Dreams from My Father, about his time with a New York girlfriend are misleading.

Maraniss writes that in the memoir, Obama distorted [Cook's] attitudes and some of their experiences, emphasizing his sense that they came from different worlds. Decades later, during an interview in the Oval Office, Obama acknowledged that, while Genevieve was his New York girlfriend, the description in his memoir was a 'compression' of girlfriends, including one who followed Genevieve when he lived in Chicago. Maraniss points out a passage from the memoir in which Obama talks about taking his New York girlfriend to a play by a black playwright and the two argued about why black people were so angry all the time -- the incident never happened with Cook, but more likely with the Chicago girlfriend.

  • He and Genevieve would often hand out with a group of Pakistanis, but Obama eventually grew apart from them.

Maraniss' interpretation: [Friend] Beenu Mahmood saw a shift in Obama that corresponded to Genevieve's perceptions. He could see Obama slowly but carefully distancing himself as a necessary step in establishing his political identity as an American. 

  • Genevieve, who is white, and Obama talked about race a lot.

According to Maraniss' research, Genevieve wrote in her journal that Obama confessed he felt like an imposter. Because he was so white. There was hardly a black bone in his body. She later wrote that in his own quest to resolve his ambivalence about black and white, it became very, very clear to me that he needed to go black. Genevieve predicted who his ideal woman might be: I can't help think that what he would really want, be powerfully drawn to, was a woman, very strong, very upright, a fighter, a laugher, well - experienced - a black woman I keep seeing her as.

Read the entire Vanity Fair excerpt here.