Other state-run exchanges have faced serious problems. In Oregon, for example, technical difficulties have prevented residents from completing enrollment, though about 4,000 people have filled out initial paperwork either online or in print.

"We're working through the problems," Cover Oregon spokeswoman Ariane Holm said. Officials hope to open the enrollment website to the public by the end of the month. "We want to make sure we get it right, not just get it out there."

Software experts question the approach that the federal government and some states took in creating the online marketplace.

Alexander Howard, a fellow at Harvard University's Ash Center for Democratic Governance and Innovation and Columbia University's Tow Center for Digital Journalism, said the federal government has a procurement problem, and some states may have fallen into the same trap. Governments often contract out large, complex systems to companies that may not be innovative and nimble enough to envision them, write code, communicate and anticipate user needs, he said.

"Maybe [the companies are] not the best at building systems, they're the best at getting government contracts," he said. "There is a thicket of rules and regulations that governs how government can buy and maintain technology."

Paul Smith, chief technology officer at Public Good Software, agreed. He headed software engineering efforts for Obama's 2012 re-election campaign while at the Democratic National Committee, and embraced cutting-edge technology more common to a Silicon Valley start-up to effectively raise donations and organize. He said rigid procurement rules limit such innovation among federal agencies.

Another issue is that the federal website and Maryland's are hitting bottlenecks because they depend on computer links to agencies, including the Social Security Administration and the Internal Revenue Service, to verify consumer information. The systems at such agencies weren't meant to handle high web-based traffic, the experts said.

The problems can be overcome with good computer code writers, enough servers, proper testing and lots of oversight, Smith and Howard said. But that takes time, and many health exchanges weren't ready by the Oct. 1 deadline for the start of enrollment.

Smith pointed out that the Medicare Part D prescription drug plan also had a rough roll out, though he suspects most people don't remember that because the program is hugely popular.

"I've been developing software for decades and it's buggy," he said. "The first time you always encounter challenges and everyone expects that with any product. ... Going forward I expect the sites to stabilize and be more responsive, and enrolling people in health care and the experience not to be a frustrating one."

If the kinks are not worked out soon, some say authorities may need to ease enrollment deadlines. The uninsured need to buy coverage by March. For coverage to begin in January, consumers must sign up by mid-December.

"There is still time," said Sabrina Corlette, a senior research fellow at Georgetown University's Center on Health Insurance Reforms. "Maryland had been seen as ahead of the pack. But now we're pointing to Kentucky as one of the only states moving smoothly. If this goes on another month, some policy decisions on open enrollment will need to be made."

meredith.cohn@baltsun.com

Baltimore Sun reporters Tim Wheeler and Scott Dance contributed to this article.

An earlier version of this article included incorrect information on numbers of applications received and enrollments completed in other states.

Health exchange enrollment

Maryland officials said that as of Oct. 10, 1,121 people have enrolled for insurance through the state's health exchange, while 16,712 had completed applications and been screened for eligibility. Here are samples from some other states:

Kentucky: 9,000-plus enrolled through Oct. 10.

New York: nearly 80,000 applications completed and eligibility evaluated as of 9 a.m. Oct. 11.

California: 16,311 applicants that had been subsidy eligibility evaluated, as of Oct. 5.

Oregon: zero

Federal system, serving 36 states including Delaware, Pennsylvania and Virginia: Statistics not available