Michelle Obama is the perfect lesson in how to do First Lady dressing: always fashionable, but assembling her outfits with judicious use of designer pieces mixed with All American staples from Gap and J Crew.

On the campaign trail with her husband yesterday, Michelle was wearing a striking green gingham print dress with a statement necklace which, on closer inspection, was revealed to be from Jason Wu's upcoming second line, Miss Wu.

Though the collection does not go on sale until January 2013, Mrs Obama has long been a supporter of Wu, most notably wearing a dress by him to President Obama's inauguration celebrations in 2009 (the dress is now in the Smithsonian Museum in Washington D.C.), so it's hardly surprising Wu gave her the chance to do some pre-launch shopping.