Washington - America flexed a toned bicep recently and onlookers cheered.

Mrs Michelle Obama, 45, floored Europe as she swept from London to Paris to Prague with her summit-hopping husband Barack Obama.

Not since Mrs Jacqueline Kennedy's 1961 tour has a US First Lady's overseas visit been lavished with such rapturous coverage.

Such was the allure of ma belle Michelle that she was deemed the winner of the face-off - as the tabloids called it - with Europe's First Lady of fashion French President Nicholas Sarkozy's wife and ex-supermodel Carla Bruni.

Now America is discovering the spin-offs of having Mrs Obama as the bearer of its image abroad. And aren't they loving it.

'Carla who?' said one British newspaper tartly.

Mrs Obama has done the traditional thing: appearing at schools in Washington DC's poor neighbourhoods, before women's groups and in soup kitchens. But she also did a tour of the federal government bureaucracies and a military base in North Carolina. Aides said she was furthering her interest in work-life-family balance issues.

It is early days, of course, and the making of the First Lady is a work in progress.

It is delicate dance, for the most part. The fact is Americans are fickle about what they want in a First Lady, a title bestowed without any official duties.

Mrs Hillary Clinton's aggressive style and ambition to frame policy were resented. Mrs Laura Bush, on the other hand, was thought to be wasting the opportunity afforded to a presidential spouse until she found her voice as a champion for literacy, Myanmar protesters and Afghan women.

What is clear is that the days of the First Lady in the traditional role as the White House hostess are long past. She can't be like Mrs Bess Truman, who once said her job was to 'sit quietly on the podium next to her husband and make sure her hat was on straight'.

Mrs Obama can aspire to be more like the trailblazing Mrs Eleanor Roosevelt, who held news conferences, wrote daily newspaper and monthly magazine columns and hosted a weekly radio show.

The comparison that still comes easiest is with Mrs Jacqueline Kennedy.

'People look at the glamour that surrounds her and say she reminds them of Jackie,' said Mr Barry H. Landau, presidential historian and author of The President's Table: 200 Years Of Dining And Diplomacy.

'Indeed, she has Jackie's youth and enthusiasm. But...she is also able to connect to people the way Eleanor Roosevelt did,' said Mr Landau, who personally knew 14 First Ladies.

'But you can also compare Mrs Obama to Mrs Ellen Wilson, the first wife of president Woodrow Wilson who in 1913 was passionate about improving housing in the capital's African-American slums. She brought them to the attention of debutantes and Congressmen. That was unheard of then.'

Mrs Obama has identified several issues as her priorities, like education and health care, and these are President Obama's top agenda items too, noted Mr Darrell West of the Brookings Institution.

'She can help by drawing public attention to these issues and by encouraging private- and public-sector leadership to address these issues.'

The Harvard-trained lawyer has yet to find her calling, so to speak. But the administration would be hard-pressed to find a better friend, given the enormous goodwill she has generated. Her approval ratings are in the 70s, higher than her husband's high 60s.

Said Mr Stephen Hess, a presidential scholar at Brookings. 'She is a presence...She can help in a 'grand' way. She need not go out to lobby for global warming agenda, for example. Goodwill for her will extend to her husband and his government.'

Asked before the presidential election about what kind of First Lady she would be, Mrs Obama had this to say: 'It's hard to know. What I do know is that given the many skills that I have on so many different levels, I will be what I have to be at the time. And it really will depend on what the country needs, what my family needs, what Barack needs. So I want to remain flexible enough so whatever is needed of me, that's what I will do.'

These are difficult times for America, in the midst of a deep recession and entangled in two wars. Can Mrs Obama chip in?

'Absolutely,' said Mr Landau. 'Her message, like her husband's, is that of hope.'