cross the country, officials are issuing warnings that despite fevered efforts, their new insurance exchanges — online markets where people can shop for health plans and see if they qualify for federal subsidies — will not be fully operational for weeks or even months.Last week, the District of Columbia’s exchange announced that it would not immediately be able to determine online whether people qualify for Medicaid, which about half the states are expanding under the law, or for a federal subsidy to help cover the cost of private coverage. In Colorado, for the first month, people who want to know if they are eligible for a subsidy will have to call a customer-service line.In Nevada, home to a large Hispanic population, a Spanish-language version of the exchange Web site will not be ready until mid-November. And in Maryland, small businesses will not be able to buy insurance for their employees through the state exchange until January. Federally run exchanges are having similar problems.Now many of the 16 directors of state-run exchanges are describing October as a “soft launch” period, when Americans can start exploring their coverage options — but on Web sites that may be incomplete, vulnerable to glitches, and perhaps not ready for a full onslaught of customers.“I have no idea what this thing’s going to look like on Oct. 1,” Mr. King said one afternoon last week as dozens of tense-looking programmers on laptops, scattered through the the exchange offices outside Portland, rushed to finish testing and fix problems. “We could crash and burn and have to close it down.”The outcome could hardly be more important for President Obama. With Republicans threatening to shut down the government unless Democrats agree to delay the law for a year, even small problems with the exchanges could be powerful fodder for the law’s opponents.In an indication of the difficulty of the job, some of the states with delays, like Oregon and Maryland, have been preparing for many months and have political leaders who strongly support the law.“It makes you wonder about the exchanges that actually have been at this a shorter period of time,” said Jon Kingsdale, a managing director at Wakely Consulting Group, who is advising several state-run exchanges. “Do they even know what their problems are?”…..Because of the errors, Ms. Kofman said, a family might be told it qualified for a tax credit of $150 a month when it was eligible for only $50.The agency will be able to determine eligibility in November, she added, and people who qualify will still be able to get subsidized coverage on Jan. 1, as originally planned.