States running their own Obamacare insurance exchanges are reporting a significant surge in sign-ups just four days before the first major enrollment deadline.

The increase has ranged from 30 percent to 40 percent in the past few weeks, according to state officials who briefed reporters Wednesday. Monday is the last day to sign up for a plan that will guarantee health coverage effective Jan. 1.

California, which has one of the most successful programs, averaged 15,000 enrollments a day last week, up from an average 7,000 a day the week before, state officials said. In all of November, 80,000 Californians picked a plan; in the first week of December, 50,000 signed up.

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"We are all still in the first inning of a nine-inning game," Covered California executive director Peter Lee said. "Friends are telling friends; family are telling family. … We are quite confident that as we go into the next half of enrollment that we will build momentum."

In Kentucky, enrollments are up 40 percent since Thanksgiving, straining the state's exchange and forcing administrators to hire dozens of extra call-center workers and application processors. "We are seeing about 3,000 people a day approved for Medicaid or a [qualified health plan]," Kentucky Health Benefit Exchange executive director Carrie Banahan said. "We started out a few weeks ago at about a thousand per day."

More than 92,000 people have gotten coverage so far.

In New York, phones at marketplace call centers are ringing off the hook, averaging between 1,200 to 1,500 calls per hour, officials say. Roughly 4,500 people are enrolling in coverage each day, state Department of Health counsel Lisa Sbrana said.

In the past week alone, they've seen a 34 percent increase in people signing up.

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"We're really happy," Sbrana said. "We're seeing a good mix of enrollees across age groups."

The uptick in demand has also been seen in Connecticut, where 47,000 people have enrolled through the exchange since October and they're now adding an average 1,400 people a day.

"One area things are not going as well for us is the call center," Access Health Connecticut CEO Kevin Counihan said. "We didn't staff up fast enough for the calls" before the Dec. 23 deadline.

Fourteen states plus the District of Columbia operate their own online insurance exchanges under the Affordable Care Act. Some states have been less successful with enrollments through the program than others. Marketplace websites in Maryland, Oregon, Minnesota and Hawaii, for example, have been plagued with technical problems similar to those that have hampered the federal HealthCare.gov, stunting enrollment.

"We've had some challenges," Washington Health Benefit Exchange CEO Richard Onizuka said. "Our system was out most of the first week of December."

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