Michelle Obama’s flair for fashion has captivated Washington and set the hearts of glossy magazine editors aflutter. She has already eclipsed Carla Bruni, the super-model chanteuse and wife of Nicolas Sarkozy, the hyperactive French president. Not since Diana, Princess of Wales, has there been such a glamorous role model at the apex of society.

In her white, one-shouldered chiffon gown, she boogied to Stevie Wonder’s Signed, Sealed, Delivered I’m Yours and slow-danced with her husband at a succession of inaugural balls. Barack Obama held her lovingly around the waist, clasping two fingers around her back, and nuzzled her. Women’s Wear Daily, the influential American fashion magazine, said her ball gown made the Obamas look like newlyweds.

By the time they reached the last ball in the marbled hall of Union Station after midnight, “Michelle looked absolutely exhausted but still managed to keep smiling. It was quite an intimate dance – they were either collapsed in each other’s arms or feeling very close to each other,” said another dancer.

Michelle, 45, has a theatrical sense of style, from off-the-rack colourful clothes from J Crew at less than $100 a throw, to pricey designer outfits such as the sparkling lemongrass matching dress and coat that she wore to the inauguration ceremony. But she is determined to carve out a role at the White House that is more than national clothes horse.

Diana, the mother of two young boys and ardent champion of the less fortunate, could prove to be an inspiration. In an interview on television immediately after the election, Michelle promised to make Malia, 10, and Sasha, 7, her priority. “The primary focus for the first year will be making sure that the kids make it through the transition,” she said. “But there are many issues that I care about . . . Both Barack and I believe we can have an impact in the DC area . . . in terms of making sure we’re contributing to the community that we immediately live in.”

Michelle intends to become first lady of the forgotten of the city of Washington, which is brutally partitioned according to race and class. The political classes are segregated from the people who serve them. The city has the highest Aids rate in the country among African-Americans and more than one in three residents are “functionally illiterate”, according to a 2007 report.

Semonti Mustaphi, a White House spokeswoman for Michelle Obama, said bringing the community together “was definitely one of her priorities”.

“She grew up in a very close-knit neighbourhood on the South Side of Chicago. It was instilled in Mrs Obama and her brother Craig at a very early age that their neighbourhood was their community and it was all about giving back. It is a big part of who she is and who President Obama is.”

On the face of it, Diana and Michelle – the one a blue-blooded English rose, the other a self-made African-American woman with slave ancestry – have little in common. Diana described herself as “thick as two short planks” while Michelle is an Ivy League-educated lawyer who was, until recently, earning considerably more than her husband working as a community adviser for the University of Chicago Hospitals.

More than anyone, Barack Obama knows that the traditional role of first lady will not satisfy his wife. She gave up work at the prestigious law firm where they met and fell in love to help to found Public Allies, a programme that helps underprivileged young people to become community leaders.

Michelle does not want to repeat the mistakes of Hillary Clinton, who thought she could be co-president until she made a hash of healthcare reform. Becoming community activist-in-chief as well as mom-in-chief to the girls could fill the gap in her glamorous, but potentially vapid new life. “I think Michelle’s gonna design her own role,” Obama said. “I think she’s going to set her own path.”

The Obamas turned the national holiday for Martin Luther King, on the eve of the inauguration, into a call to “national service”, and the Obama campaign used its vast e-mail list of 13m supporters to coordinate volunteer activities all over America. In Washington, Obama visited a homeless shelter for teens and spruced up the walls with a paint roller.

“Given the crisis that we are in and the hardships that so many people are going through, we can’t allow any idle hands,” Obama said. Michelle handed out food bags for US troops and has promised to make the welfare of military families serving in Iraq and Afghanistan a priority.

Angela Kennedy Acree, Michelle’s roommate at Princeton University, predicted that the White House “will be much more accessible” now that Michelle is first lady.

“She said to me before the election and since that she’s going to open up the White House to the community and particularly to children.” Malia and Sasha will have “friends in and out” and “there’ll be many, many more regular DC kids saying, ‘I went to the White House’ . . . Kids whose parents don’t have connections or money.”

On the family’s first day at the White House, the “first tweens” invited some friends from their private school, Sidwell Friends, to a scavenger hunt at the White House. At the end of the hunt they found the Jonas Brothers, the boy pop band, lurking behind the door.

But ordinary people got a look-in as well. Barack and Michelle Obama opened the doors of the White House to a few hundred wellwishers the day after the inauguration. Some had tickets, but Paula Peebles had turned up at the east gate on the spur of the moment.

A Secret Service agent told her she couldn’t get in, but she stayed patiently in line anyway. Eventually a guard came. “He told us Michelle Obama looked out of the window and saw people waiting and told them to let the people in,” said Peebles.

The Obamas greeted the visitors in the oval room. “Welcome, enjoy yourself. Don’t break anything,” Obama said.

Prince Charles was never comfortable with Diana’s visits to Aids sufferers and the homeless, regarding it as a sign of her neediness, not theirs. The opposite is true with Obama. He will have his hands full with two wars and the worst economic crisis since the Great Depression.

“For as much as government can do and must do, it is ultimately the faith and determination of the American people upon which this nation relies,” Obama said in his inaugural address. “What is required of us now is a new era of responsibility.”

And for that, the new president is going to rely on his wife.

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