Most of the top names in fashion rave about Michelle Obama's sartorial choices. But not Oscar de la Renta.

The legendary American designer let the first lady have it after she wore a red gown from the British design house of Alexander McQueen to a state dinner for Chinese president Hu Jintao at the White House last week just as her husband bluntly told Hu "we want to sell you stuff."

"My understanding is that the visit was to promote American-Chinese trade," de la Renta told Women's Wear Daily. "Why do you wear European clothes?"

He has a point. You can bet Kate Middleton won't be wearing a wedding gown from an American designer at her April wedding.

But it is something else de la Renta noted in the interview that caught my eye.

"You don't...go to Buckingham Palace in a sweater," he said disapprovingly about the J Crew cardigan the first lady wore when she met Queen Elizabeth II two years ago.

I thought the same thing recently when I spotted the first lady in a cardigan sweater at the service at the University of Arizona honoring those killed and injured in Tucson. It seemed far too casual for such a solemn occasion.

And just last weekend she wore an odd-looking black leather jumper by British designer Jonathan Saunders to Sargent Shriver's funeral. It also seemed out of place, especially when she stood next to Caroline Kennedy, who was wearing a simple black dress.

It made me wonder who's been advising the first lady on what to wear lately. Mrs. O, a fashion blog that chronicles everything the first lady wears, whispers that a "shadow stylist" rumored to be 28-year-old White House aide Meredith Koop is reponsible for her recent shift to a diverse group of fashion-forward designers like Dries Van Noten, Marc Jacobs, Roksanda Ilincic, and even vintage Norman Norell. The first lady is believed to have previously relied on Chicago boutique owner Ikram Goldman for fashion advice.

It's no secret Michelle Obama loves fashion and is not afraid to take chances — whether it's bare arms in the winter or short shorts in the summer — a refreshing change from the country club looks that her predecessor, Laura Bush, favored. (Quick, can you recall anything that Bush wore in her eight-year tenure as first lady?)

After Barack Obama was elected President in 2008, the fashion press, many who had contributed heavily to his campaign, hailed Michelle as the next Jackie Kennedy. That notion was quickly dispelled at the inauguration when she wore an ill-fitting Jason Wu gown that resembled a chenille bedspread. Nevertheless many in the fashion world have continued to praise her fashion sensibility even though she alternates between sartorial hits and misses.

For an audience with Pope Benedict XVI in 2009, she wore a black Moschino blouse with a huge bow — a big fashion mistake. And, at the recent state dinner, the Alexander McQueen gown, from designer Sarah Burton who assumed design duties after McQueen committed suicide last year, looked a little too beauty-pageant-like, although the red color has special significance in China.

Obama looked stunning at two previous state dinners. She wore a shimmery blue gown with a silver belt by Peter Soronen at a state dinner for Mexican President Felipe Calderon last May and a stunning sleeveless sequined gold gown and shawl by Naeem Khan at a state dinner for Indian Prime Minister Manmohan Singh last November.

At Tuesday night's State of the Union address, she wore a conservative gray sheath with three-quarter sleeves and a rounded neck by Rachel Roy that was classy yet fit in with the subdued nature of the occasion. She accessorized it with several silver bangles on her left wrist and a white ribbon pinned to her dress to salute Arizona congresswoman Gabrielle Giffords, who is recovering at Memorial-Hermann Texas Medical Center Houston hospital.

The first lady has earned justifiable praise for championing a slew of little-known designers like Wu, Soren, Thakoon, and Narciso Rodriguez. At the same time, some have wondered why she has shunned more established designers like Ralph Lauren, Donna Karan, Calvin Klein, de la Renta and Vera Wang, who was invited to the China state dinner and would have been a logical choice to design a gown for the occasion.

Athough he was favorite of previous first ladies Laura Bush and Hlllary Clinton when they were in the White House, de la Renta said his complaints about the first lady's decision to wear a British designer aren't meant to be sour grapes.

"I'm old, and I don't need it," de la Renta said. "But there are a lot of young people, very talented people here who do."