Sheryl Gay Stolberg and Susanne Craig / New York Times News Service

WASHINGTON — A little more than 106,000 people picked health plans in the first month of open enrollment through the state and federal insurance marketplaces established by the Affordable Care Act, President Barack Obama’s health secretary said Wednesday — a fraction of the administration’s initial estimate for enrollment for that period.

Only about a fourth of the new enrollees — 26,794 — signed up through the problem-plagued federal exchange,, according to figures released by the Centers for Medicare and Medicaid Services. A much larger number signed up through the 14 state-run marketplaces.

The long-awaited figures, released by Kathleen Sebelius, the secretary of health and human services, became instant fodder for the continuing political battle over Obama’s signature legislative initiative. As nervous Democrats on Capitol Hill threatened to introduce legislation altering the law, Republicans called the new numbers dismal and cited them as further proof that the program was a “train wreck.”

The White House has spent weeks trying to lower expectations — even as questions emerged about the way it counts who is enrolled. On Wednesday, Sebelius and congressional Democrats were upbeat, saying people were clearly shopping for coverage.

“The marketplace is working,” Sebelius said. “People are enrolling.”

The nonpartisan Congressional Budget Office has predicted 7 million people will enroll by the time the initial sign-up window closes on March 31, and administration officials insist they can meet that goal. But the numbers released Wednesday fall far short of the administration’s early projections, contained in an internal memo in September, which said 464,920 would sign up in the first month.

A peek into state data reveals vast disparities. Florida, the state with the second-highest number of uninsured (behind Texas), had the most enrollees in the federal-run exchange, 3,571. Texas was second, with 2,991. There were just 42 in North Dakota.

In explaining the relatively low enrollment figures, administration officials cite problems with the federal website, which have clearly prevented people from signing up. But they also cite the experience of enrolling people under the Massachusetts health law, which suggests that many people enroll at the last minute.

When that state expanded health coverage, only 123 of the 36,167 people who ultimately signed up did so during the first month of enrollment. But more than 7,000 signed up during the final month. (Massachusetts, though, unlike the Obama administration, counted only people who had already paid their premiums as enrollees, according to Jon Kingsdale, who ran that state’s health insurance exchange.)

There is still one month to go until the Dec. 15 deadline for signing up for coverage that begins Jan. 1; the initial enrollment period does not close until March 31. So administration officials, and some outside experts, say these early numbers do not reveal much.

“These numbers are interesting,” said David Simas, the White House point man on the health law, “but in terms of any kind of insight into the success of the program, they’re not the central indicator.”

In political terms, though, the numbers are yet another problem for the White House, which is one reason Sebelius — and not the president — announced them on Wednesday. Republicans insist there is no way the administration can reach its goal.

“By the time we reach the critical month of December, actual enrollment could lag projections by over 1 million people,” Rep. Dave Camp, R-Mich. and chairman of the House Ways and Means Committee, wrote in a letter this month, accompanying a subpoena for detailed enrollment data. In an interview, he said the enrollment figures were only one part of the story.

“It’s not just about the top-line number,” he said. “What I want to know is the mix of these people. What kind of insurance are they getting? What age are they?”

Sebelius said Wednesday that her agency would release that kind of data at some point; she did not say when. But experts on all sides of the debate agree that the “mix” — how many are young and healthy, versus how many are old and sick — may be far more important than the actual enrollment numbers. If not enough young, healthy people enroll, premiums will skyrocket, and the law’s promise of “affordable care” will not be realized.

“The mix is valuable for insurers, because it will result in more stable premiums. If all the people who enroll are very sick, they will have to raise premiums next year, and that is a problem,” said Dan Mendelson, the chief executive of Avalere Health, a health care advisory firm.

Democrats begin to back changes to the Affordable Care Act

WASHINGTON — Anxious congressional Democrats are threatening to abandon President Barack Obama on a central element of his signature health care law, voicing increasing support for proposals that would allow Americans who are losing their health insurance coverage because of the Affordable Care Act to retain it.

The dissent comes as the Obama administration released enrollment figures Wednesday that fell far short of expectations, and as House Republicans continued their criticism of administration officials at congressional hearings examining the performance of the health care website and possible security risks of the online insurance exchanges.

In addition, a vote is scheduled Friday in the Republican-controlled House on a bill that would allow Americans to keep their existing health coverage through 2014 without penalties. The measure, drafted by Rep. Fred Upton, R-Mich., the chairman of the Energy and Commerce Committee, is opposed by the White House, which argues that it would severely undermine the Affordable Care Act by allowing insurance companies to continue to sell health coverage that does not meet the higher standard of Obama’s health care law.

But a growing number of House Democrats, reflecting a strong political backlash to the rollout of the law, are warning the White House that they might support the measure if the administration does not provide a strong alternative argument. The approaching House vote is shaping up as an important test for both the health measure and the unity that Democratic leaders have so far been able to maintain around it despite a fierce Republican attack.

In a closed-door meeting Wednesday of House Democrats and White House officials, tensions flared as several lawmakers upbraided the administration, saying that the president had put Democrats in a tough political position by wrongly promising consumers that they could keep their existing health care plans. In fact, hundreds of thousands of Americans have received cancellation notices from their insurers because their health care coverage does not meet the minimum standards dictated by the new law.

“I’m frustrated in how it rolled out, and I let them know in no uncertain terms,” said Rep. Mike Doyle, D-Pa. “The point I was making in caucus to the administration is don’t give us this techno-babble that you’re going to do some administrative fix down the road. There’s a bill being put on the floor on Friday.”

The overall message of the meeting, said several attendees, was that the White House and the House Democratic leadership have until Friday to come up with a satisfactory alternative, or House Democrats might be forced to support Upton’s bill, which has two Democratic co-sponsors: Reps. John Barrow of Georgia and Mike McIntyre of North Carolina, who represent more conservative districts.

“I think the Upton bill is terrible, but we need something else to vote for in order to keep our word to the American people,” Doyle added. “We told people in those plans that they were grandfathered in, and if they wanted to stay in them, they could, and we need to honor that.”

— New York Times News Service