Around 100,000 Americans successfully signed up for health insurance in November through the troubled federal online marketplace, HealthCare.gov, a person familiar with the preliminary data confirmed to ABC News.

The figure reflects a surge in enrollment as software and hardware fixes to the site were made over the course of the month. In October, only 26,000 people could successfully enroll in Obamacare plans, according to the Department of Health and Human Services.

"We've been working 24/7 to make improvements, and more consumers are successfully shopping online and enrolling in a health plan each week," Health and Human Services Secretary Kathleen Sebelius wrote in a USA Today op-ed.

While the administration says the latest enrollment data is "still being scrubbed," the early November numbers underscore that sign-ups are still far short of White House monthly targets and behind pace for a goal of 7 million enrollments by March 31.

Before the website launch, the administration projected signing up half a million Americans for new health insurance coverage in October alone.

Fourteen states plus the District of Columbia, which run their own online exchanges, have generally fared better than the federal government in enrolling new customers. They have also seen a surge in sign-ups through mid-November, topping more than 94,000 in early data compiled by the independent Commonwealth Fund.

On Sunday, the White House announced that the federal online marketplace was vastly improved and will now work smoothly for the "vast majority" of users. The administration is beginning a campaign to drive consumers back to the site to complete their applications and enroll.

More than 975,000 Americans completed an application in October but did not select a plan and finalize enrollment, according to Health and Human Services.

"As a result, today's user experience on HealthCare.gov is a dramatic improvement over where it was on Oct. 1. The site is running faster, it's responding quicker and it can handle larger amounts of traffic," Sebelius wrote.

Consumers still have four months to sign up for insurance to be in compliance with the Affordable Care Act's individual mandate. The deadline to enroll for coverage to take effect in early 2014 is Dec. 23.

Meanwhile, health insurance companies say there are serious and unresolved problems with the backend of the enrollment system, particularly with the electronic data they receive about applicants. Insurers said some of the data continues to be unreliable, often in duplicate, incomplete or error-riddled.

"Healthcare.gov and the overall enrollment process continue to improve, but there are significant issues that still need to be addressed," said Karen Ignani, president and CEO of America's Health Insurance Plans.

"Until the enrollment process is working from end-to-end, many consumers will not be able to enroll in coverage. In addition to fixing the technical problems with healthcare.gov, the significant 'backend' issues must also be resolved to ensure that coverage can begin on Jan. 1, 2014," she said in a statement.

The preliminary federal online enrollment figure for November was first reported by Bloomberg News.

ABC News' Rick Klein contributed reporting.