"We need to convince the consumer," said McComb on the fourth-quarter earnings conference call on March 14. "We need to leverage all of the marketability and buzz factor that Isaac can bring."

In the '70s and '80s, Liz Claiborne offered droves of women just entering the workforce an alternative to suits inspired by menswear. She created affordable, pretty separates that busy working women could easily combine into different outfits. To bring back that practical femininity, Mizrahi must pull off three feats: First, he has to translate the design skills he's proved at the high end, with his couture lines sold at Bergdorf Goodman, and low end, with his $420 million Target business, to a crowded middle market. Second, à la Karl Lagerfeld at Chanel, he has to concoct a clever mix of history and one of fashion's holy grails, "newness," channeling Liz's legacy of affordable ensembles while making the collection exciting for 21st-century women. Lastly, he must live up to his hype with hits—quickly—or Liz will lose more of the retail floor space it's barely hanging on to now.

"From the consumer's perspective, he's got two seasons," says Marshal Cohen, chief industry analyst at trend-tracker NPD Group. "If you don't hit a home run within spring or fall, they don't have that long of an attention span."

Sources say Mizrahi will be remaking Liz with colorful clothes that combine femininity and professionalism. That's what he's done at Target for the past five years, producing stylish takes on work-appropriate coats, dresses, and suits, like the flared, box-pleat jacket with a Peter Pan collar, and the lipstick-pink retro shirtdress featured this spring.

"Liz Claiborne, what they've done in the past doesn't come across as particularly feminine," says Roseanne Morrison, fashion director at retail-trend forecaster and consultant Doneger Group. "What Isaac has done had a certain mood, and hopefully he will translate that for Claiborne."

As the first creative director to oversee the entire Liz Claiborne brand for women since its namesake founder, Mizrahi is regarded as the company's best hope to restore its heritage. The legendary Liz Claiborne retired in 1990, and died last year.

"Liz needed a big persona and big shot in arm," says Krupp. "And if it doesn't work with Isaac, call it a day."