ANALYSIS: Michelle Obama a Tough Act to Follow in a Tough Job

— -- Melania Trump has a tough act to follow.

Michelle Obama leaves the White House with sky-high approval ratings after a campaign season where enormous and enthusiastic crowds jammed into her every appearance, shouting that she should to run for office. Retrospectives of the Obama presidency praise everything from her healthy food to her high fashion.

But in fact, just about every first lady comes into office at a disadvantage. (Except perhaps the first White House hostess dubbed “first lady” by the press. James Buchanan’s niece, Harriet Lane, moved in after Jane Pierce spent her four years in the Executive Mansion mourning the death of her son, causing one writer to judge: “her woebegone face… banished all animation in others.”)

The title comes with no job description, and a great deal of suspicion. The public knows that the president’s wife is likely to have a great deal of influence but she can’t be fired. And each first lady is pretty much left to figure out how to handle it for herself. One exception: Laura Bush and her staff worked to make smooth her successor’s path.

Even so, Michelle Obama took some time to get comfortable in the role, to choose the causes where her voice would make a difference and to organize the allies to work with her to bring about change.

Mrs. Obama was at something of a disadvantage because she had never been first lady of a state. For both Laura Bush and Hillary Clinton that experience had provided the closest thing to a test run for the national role. Not only had they learned how to promote their projects, they also already knew what it was like to take hits from political opponents and the press.

Melania Trump will arrive with none of that preparation and with no close friends nearby as she tries to navigate through the treacherous waters of the nation's capital. Much has been made of the fact that she is not the first first lady to be foreign born -- that distinction goes to Louisa Catherine Adams, the wife of John Quincy.

But Mrs. Adams was the daughter of an American living in London at the time of her birth. By the time she went to the White House her husband had served in the Senate and for eight years as secretary of state. She was so wily about the ways of Washington that she wrote her father-in-law that it was her “vocation” to get her personality-challenged spouse elected president. No neophyte she.

Contrast that with Melania Trump, who will be thrust into this very public position with no political preparation beyond the recent campaign. Michelle Obama and her staff have offered to be helpful and Mrs. Trump would be wise to accept those offers. She just has to hope that her husband doesn’t tweet something that offends the people who want to give her a helping hand.

Cokie Roberts is a political commentator for ABC News. Opinions expressed in this column do not necessarily reflect the views of ABC News.