The White House is increasing its reliance on insurers by accepting their technical help in efforts to repair the problem-ridden online health insurance marketplace and prioritizing consumers' ability to buy plans directly from the carriers. The Obama administration's broader cooperation with insurers is a tacit acknowledgment that the federal insurance exchange — fraught with software and hardware flaws that have frustrated many Americans trying to buy coverage — might not be working smoothly by the target date of Nov. 30, according to several health experts familiar with the administration's thinking. White House officials reject the idea that the strategy represents a contingency plan in the event that the online system continues to falter.