In 2004, Michelle Obama was the wife of a Democratic state Senator in Illinois. When her husband said he wanted to run for the U.S. Senate, she laid out all the reasons he shouldn’t run for another public office. Finally, she conceded, joking, “Maybe you’ll lose.”

Little did she know that only a few months later now-Sen. Barack Obama (Ill.) would become the Democratic Party’s rising star after giving the keynote address at the national

convention in Boston. His campaign had planned an RV trip through rural southern Illinois for the week after the convention, and Michelle and their two young daughters came along to get some time with their husband and father. It was supposed to be a relaxing campaign swing with stops to eat ice cream and see petting zoos.

Instead, crowds of more than 500 or even 1,000 greeted them where they had prepared for the usual crowds of 150. Since it was supposed to be a respite after the convention, Barack himself was upset and Michelle was faced with a growing problem.

“This was the situation with which Michelle was now dealing; it was everybody’s job to get Barack elected, and nobody’s job but hers to protect his role as father and husband,” Liza Mundy wrote in her new book, “Michelle: A Biography.” “She was now, in some ways, at cross-purposes with Obama’s dynamic staff, trying to preserve even one day a week in which Barack Obama would belong to the Obama family and not to the Obama campaign.”

It wouldn’t be the last time her husband’s political career interfered with Michelle’s efforts to maintain some semblance of a normal family life for her children. Though she has been painted as an angry foil to her husband’s optimistic persona, Michelle sees herself primarily as the mother to the couple’s two daughters, Malia and Sasha.

In this biography, Mundy said she strove to give readers “a fuller sense of who [Michelle] is and where she comes from.” She uncovered some of the book’s most revealing details when she went to Chicago and looked into Michelle Robinson’s childhood, starting with her father’s decision to move to Chicago from South Carolina and his later involvement with politics in the Chicago machine.

Michelle, a descendant of slaves, was born six months before President Lyndon Johnson signed the Civil Rights Act into law. She grew up on the South Side of Chicago in a neighborhood where white people moved out as black people moved in, and she would have been conscious of places she could and could not go.

Yet while those experiences may have given her reason for the bitterness some critics detect in her public comments, Mundy said that Michelle had plenty to be grateful for: a supportive, two-parent family; education at an integrated, cozy magnet high school followed by Princeton University and Harvard Law School; a job at a prestigious law firm after she graduated — all eventually culminating in the possibility of becoming first lady.

“The day she was born, Michelle Robinson embodied the unique combination of discrimination and opportunity, hardship and overcoming, of being acted upon and acting, that would define much of black history in America,” Mundy wrote.

Mundy, a Washington Post staff writer, first wrote a profile of the Illinois Senator last year. She spent three to four months researching and interviewing the new presidential candidate and in August produced an 8,655-word profile titled “A Series of Fortunate Events.”

Last winter — she remembers it was about the time the Senator’s wife was making appearances in South Carolina — an editor asked if she would write a biography of Michelle Obama.

The author said she has a lot in common with Michelle. She arrived at Princeton three years before Michelle and less than a decade after the university began admitting women in 1969.

“Women had been there for an even shorter period of time than African-Americans had been admitted, so when I started in ’78, women had just been there for nine years,” Mundy recalled. “So I don’t know how much of Michelle’s experience was influenced by being female, but I certainly saw the ways, as I wrote, many of the clubs and institutions had not had female presidents.”

Like Michelle Obama, Mundy has two children, one almost 13 and the other 10. Her husband’s job in counterterrorism, she said, often means that she is the one who has to make herself available to her children, much like Michelle.

Mundy said that if she had gotten better access and more time for the biography, she would have devoted more time to the Obama daughters, and that if Obama wins the presidency, she’d like to update the biography. For this edition, though, she had only about six months, working uphill after the campaign decided not to cooperate and discouraged friends and family from talking to her.

Though Mundy’s book is the first printed biography of Michelle Obama, it’s not the only biography available. Globe Pequot Press is also offering biographies of both potential first ladies, but with a twist: Elizabeth Lightfoot’s “Michelle Obama: Grace and Intelligence in a Time of Change” and Alicia Colon’s “Cindy McCain: Elegance, Good Will and Hope for a New America” are now available exclusively on Kindle, Amazon.com’s electronic reading device. Only the biography of the woman whose husband wins the presidential election will be published as a physical book, according to Robert Sembiante, a spokesman for Globe Pequot. Mundy’s offering, meanwhile, is available in hardcover from Simon & Schuster.