Before he was the 44th POTUS and Michelle’s husband, Barack Obama was a regular sex machine — so good that a gal pal wrote poems about their lovemaking, a new biography claims.

“B. That’s for you. F’s for all the ­f—ing that we do,” gushed Genevieve Cook, an Australian-born woman who hopped in the sack with the then-22-year-old Obama after their very first date in Manhattan.

“We went and talked in his bedroom. And then I spent the night. It all felt very inevitable,” Cook wrote in the diary, which was revealed in the biography, “Rising Star: The Making of Barack Obama.”

Obama had just graduated from Occidental College in LA and was working in Manhattan in 1983 when he met Cook, the well-traveled daughter of an Aussie spy and diplomat who was three years Obama’s senior.

“All this f—ing was so much more than lust,” the book quotes a passage from her diary, according to the Daily Mail. “Making love with Barack, so warm and flowing and soft but deep — relaxed and loving — opening up more.”

Their first night spent together came after they had dinner in his apartment on West 114th Street, according to Cook.

“The thing that connected us is that we both came from nowhere — we really didn’t belong,” she recalled. “Sexually he really wasn’t very imaginative but he was comfortable. He was no kind of shrinking ‘can’t handle it. This is invasive’ or ‘I’m timid’ in any way; he was quite earthy.”

During their relationship, the two enjoyed cocaine together, the book claims — though Obama was not that into it. “For every five lines that somebody did, he would have done half,” Cook said.

The book also details the live-in lover whose hand in marriage Obama asked for twice — and with whom he cheated on Michelle in the early days of their relationship.

The first refusal from Sheila Miyoshi Jager, who is now an Oberlin College associate professor, came because her mom thought she and Obama — who were 23 and 25, respectively — were too young.

But her second refusal came as the Harvard-bound Obama wrestled with his political and romantic aspirations — and what he saw as the advantages of marrying a black woman if he was to someday ascend to the presidency.

Jager is of Dutch and Japanese heritage. “He felt trapped between the woman he loved and the destiny he knew was his,” biographer David Garrow writes.

Obama and Jager kept seeing each other, even as Obama began a new relationship with the woman he’d take all the way to the White House, Michelle Robinson, the book says.

“I always felt bad about it,” Jager said of their continuing to see each other, off and on, as his romance with Michelle blossomed.

Ultimately, while still in his mid-20s, Obama broke it off with Jager entirely.

Obama realized “he had to fully identify as African-American,” Garrow writes of the then-community organizer mulling his first high-profile political run.

“For black politicians in Chicago, [Garrow] writes, a non-African-American spouse could be a liability,” the Washington Post review notes of Obama’s reasoning.

“If I am going out with a white woman, I have no standing here,” Garrow says Obama told a friend at the time.

It was a damningly calculated trade-off, Garrow writes.

“While the crucible of self-creation had produced an ironclad will,” he writes, “the vessel was hollow at its core.”

Despite her huge role in his 20s, Jager would be almost entirely omitted from Obama’s own memoir, “Dreams from My Father.”

While at Harvard Law School, Obama gained a reputation as an annoyingly compulsive orator, says Garrow, who won a Pulitzer Prize for his biography of Martin Luther King Jr. In his late 20s, Obama had the irksome habit of summarizing other people’s arguments for them, the book reveals.

“In law school, the only thing I would have voted for Obama to do would have been to shut up,” one student told Garrow.

Classmates created an “Obamanometer,” to rank “how pretentious someone’s remarks are in class,” Garrow writes.

The 1,078-page book is set to be released on May 9.

Among the more shocking revelations, according to Garrow, was that Obama briefly considered pursuing a relationship with a much-admired professor at Occidental.

It was the winter of 1980, and Lawrence Goldyn, a Ph.D. and political science instructor, had “made a huge impact on Barry Obama,” Garrow writes, according to the Mail.

The professor — who was considered fun and engaging by the students in Obama’s class — was one of the first openly gay people that the future president ever met in his life, and their friendship “helped to educate me,” Obama once said, according to Garrow’s reporting.

Obama would later confide to a girlfriend that “he had thought about and considered gayness but ultimately decided that a same-sex relationship would be less challenging and demanding than developing one with the opposite sex,” Garrow writes.

NEW YORK POST