(This story first appeared on DNAInfo.com.)

Mayor Bill de Blasio has promoted his pre-K expansion as a way to help working families — but programs that last only about six hours a day aren't long enough for many New Yorkers, parents and advocates said.

Although the thousands of new public school pre-K seats being created this year are called "full-day," they run on a typical school day schedule, from about 8 a.m. to 2:20 p.m., with summers and vacations off.

That's why many low-income families have been turning to the 350 community-based organizations that provide pre-K classes that last 10 hours per day and run year-round. As part of city's Early Learn program, these organizations offer low-cost pre-K seats using federal, state and city funding.

However, the thousands of new pre-K seats de Blasio plans to create over the next two years at community-based organizations will only have enough funding to cover the school day schedule of about six hours a day, 10 months per year, officials said — raising concerns that they will not adequately serve some of the families de Blasio had pledged to help.

David Nocenti, executive director of Union Settlement, which runs seven early childhood centers in East Harlem, praised de Blasio's efforts to expand pre-K, but he worries his nonprofit won't be able to provide the same level of services under the new program.

"Without additional funding, we could end up with one classroom of 4-year-olds receiving a full day of educational programming throughout the year, and a second classroom of 4-year-olds in the same center, whose day ends at 2:20 p.m., and whose classrooms will be closed in July and August," said Nocenti, whose organization applied to add about 36 new pre-K seats this fall.

"This will create tremendous hardships for the parents of this second group of children, who will have to figure out how to obtain care for their children in the afternoons and the summers," Nocenti added, "particularly since there is a dearth of free or low-cost afterschool and summer programs for 4-year-olds."

For Tanesha Shell, a single mom from Harlem who works full-time, being able to drop her 4-year-old son, Rodney, off at Leggett Memorial Day Care Center for 10-hour days has been a huge help.

"With public school, you have to find a summer camp or a relative to take care of your child," said Shell, whose son began attending Leggett, one of Union Settlement's centers on East 104th Street, when he was 2 years old. (Early Learn provides services from kids ages 6 weeks to 5 years.)

"He's not just being babysat," she added. "By the time he was 3 he was reading. He can count to 100. He can tell me days of the week and months of the year."

Scrambling for after-school care is not a new problem for parents of children of many ages, but the lack of afterschool programs for 4-year-olds could prevent some families from enrolling in de Blasio's new pre-K seats, experts said.

"Providing care for extended hours, whether in a [community-based organization] or a public school after-school program, is a necessity for working families," said Maria Fitzpatrick, a professor of policy analysis and management at Cornell who has written extensively on early childhood education.

"Providing such wrap-around care would allow pre-K to have the most success at increasing enrollment, particularly among the families who benefit from it the most."

De Blasio has acknowledged that the new six-hour pre-K seats aren't "perfect," but he said they are better than some of the current options, which include half-day seats in public schools that last less than three hours.

"What we heard of from parents all over this city is that the worst of all options was just having three hours because they understood that their children weren't getting enough opportunity to learn, and very few parents have the flexibility to match around a three-hour system," de Blasio said at a pre-K press conference last month.

"Now if you have a system that goes a full school day, then there are some options, at least, you can turn to," he added, "to cover the rest of the time until a parent might come home, or parents may have enough flexibility in their schedule."

Department of Education officials did not respond to questions last week about whether the city would seek additional funding to extend the pre-K day at community-based organizations that serve low-income families.

Officials added that one advantage of the new seats, is that while they may be shorter than Early Learn's, they are free and open to everyone.

Early Learn pre-K programs, on the other hand, limit who can attend based on the federal funding they receive. Families must meet income restrictions (a family of three can't earn more than $39,000, for instance), along with work requirements (including six weeks worth of pay stubs needed to enroll). The programs require families to fill out extensive paperwork and they also charge parents from $15 to $100 a week.

For Shell, the onerous application and fee were worthwhile, because otherwise, she said, she would have to pay a babysitter hundreds of dollars a month so she could work.

"I saved a lot," Shell said.