Diageo's Smirnoff and Pernod Ricard SA's Absolut are clinging to their collective one-fifth share of the $18 billion US market for the liquor after failing to stem a consumer shift toward independent producers and a whiskey resurgence that's kept vodka consumption flat for more than three years. The brands, which contribute more than a quarter of US sales for both companies, are discounting products, restyling themselves and recruiting legions of energetic bar-hoppers in an effort to woo a new generation of Cosmopolitan and Bloody Mary drinkers.