Even with its health insurance marketplace floundering for the fourth week, the Obama administration is resisting what some Democratic allies contend is the most logical response to the problem: giving consumers more time to sign up. According to insurers and the White house, delaying the deadline could undermine efforts to lure a broad, young and healthy mix of consumers to the market. That would end up costing insurers, and possibly taxpayers, money. The case against delay was outlined in a memo circulated to lawmakers by the insurance lobby last week. The document from America's Health Insurance Plans warned that delay could have a "destabilizing effect on insurance markets, resulting in higher premiums and coverage disruptions for individuals and families."