This March 1, 2014 file photo shows part of the website for HealthCare.gov as photographed in Washington. Welcome news for the Obama administration: A major new survey out Monday says the U.S. uninsured rate kept dropping last month and it’s now on track to reach the lowest levels since 2008, before President Barack Obama took office. The Gallup-Healthways Well-Being Index finds that 15.9 percent of Americans lack health insurance so far in 2014, down from 17.1 percent in the last three months of 2013. Gallup interviewed more than 28,000 adults, making the results highly accurate. (AP Photo/Jon Elswick, File)

WASHINGTON (AP) — The Obama administration's health care website stumbled early Monday, falling out of service for nearly four hours on deadline day for sign-ups. After it was fixed, officials plowed ahead with a nationwide promotional drive, almost like getting out the vote on Election Day.

Early visitors to HealthCare.gov on Monday morning saw messages that the site was down for maintenance. At times the visitors were also directed to a virtual waiting room — a feature designed to ease the strain on the site during periods of heavy use.

Administration spokesman Aaron Albright said the website was brought back up shortly before 9 a.m., Eastern time. But people who missed their window sign up may still be able to take advantage of a grace period and other special extensions announced last week.

Albright said the site undergoes "regular nightly maintenance" during off-peak hours and that period was extended because of a "technical problem." He did not say what the problem was, but a statement from the Department of Health and Human Services called it "a software bug" unrelated to application volume.

Albright said consumers who left an email address would be "invited back" when the system got up and running again.

Officials said the website wasn't hacked. The site, which was receiving 1.5 million visitors a day last week, received about 1.7 million on Sunday. The federal site serves 36 states. Fourteen states and the District of Columbia are running their own sites, some of which have been crippled by technical problems.

Nonetheless, the administration and the states appear to be on track to sign-up about 6.5 million people for subsidized private health insurance through the new online markets. That's half way between a revised goal of 6 million and the original target of 7 million. The earlier goal was scaled back after the website's disastrous launch last fall, which kept it off-line during most of October.

It is unclear how many consumers who have signed up ultimately closed the deal by paying their first month's premium. Also unknown is how many were previously uninsured — the real test of President Barack Obama's health care overhaul law.

Albright said Monday morning that the website is typically down for maintenance during the period from 1 a.m. to 5 a.m. EDT, and that as a result of the technical problems the site was down for close to four additional hours before returning to full strength.

The sign-up website had been taken down briefly Friday, with consumer interest surging.

A recent analysis for The Associated Press by the performance-measurement firm Compuware found that the government site runs slow compared with health insurance industry peers.

With long lines reported at centers offering in-person assistance to enroll, HHS Secretary Kathleen Sebelius was leading the deadline day sign-up effort. Sebelius planned to spend much of the day Monday working out of the department's TV studio, conducting interviews by satellite with local media stations around the country.

Although March 31 was the last day officially to sign up, millions of people were potentially eligible for extensions granted by the administration for various reasons.

That includes consumers who had begun enrolling by the deadline but didn't finish, perhaps because of errors, missing information or website glitches. The government says it will accept paper applications until April 7 and take as much time as necessary to handle unfinished cases on HealthCare.gov. Rules may vary in states running their own insurance marketplaces.

The administration is also offering special extensions to make up for all sorts of problems that might have kept people from getting enrolled on time: Natural disasters. Domestic abuse. Website malfunctions. Errors by insurance companies. Mistakes by application counselors.

To seek a special enrollment period, contact the federal call center, at 1-855-889-4325, or the state marketplace and explain what happened. It's on the honor system. If the extension is approved, that brings another 60 days to enroll.

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Associated Press writer Connie Cass contributed to this report.

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