WASHINGTON — The Obama administration is making a second attempt to regulate the way the country prepares its classroom teachers, saying training programs should be held accountable to improve the quality of K-12 teachers.

Education Secretary Arne Duncan said that his department will propose regulations for teacher training programs this summer and seek public input in a process that should result in final rules in a year.

“Far too many teachers I talk with feel teacher prep programs simply aren’t preparing them for the realities of the difficulties and hard work” they face in the classroom, Duncan said Thursday, adding that teachers complain they didn’t get enough time inside actual classrooms while they were training. “Often, the majority of teachers are saying they weren’t prepared.”

Approximately 1.6 million teachers are expected to retire this decade, and Duncan said his agency wants to support quality training programs and weed out those that are weak.

“Programs that are producing teachers where students are less successful, they either need to change or do something else, go out of business,” he said.

Some professions have standardized systems and national exams to ensure consistency. Medical students, for example, undergo a four-year program and a residency before taking a state licensing exam and national board exams, all designed so new physicians have the same core knowledge and practical skills.

But teacher preparation programs vary from school to school, and each state sets its own licensing requirements. Most programs are run by universities, but some are run by nonprofit groups or school districts. They each have their own standards of admission and completion requirements.

One obvious shortcoming of U.S. teacher training programs is the fact that few track their alumni to learn how they perform once they begin teaching, Duncan said.

Proposed regulations would require education schools that receive some federal funding to try to measure the job performance of their alumni, he said.

Randi Weingarten, president of the American Federation of Teachers, has proposed a standard entry test for the teaching profession, similar to the bar exams that lawyers must pass. She said the country needs a “systemic approach to preparing teachers and a higher threshold to ensure that every teacher is ready to teach on his or her first day in the classroom” and not “quick-fix, test-and-punish, market-based ranking of programs.”

This is the second time the department has tried to regulate the way that schools of education prepare teachers.

An earlier administration effort to set teacher preparation reporting and accountability rules collapsed in 2012. The Education Department had proposed requiring states to rate their teacher-preparation programs using a variety of measures, including test scores from students the teachers went on to have in class. But, mirroring a larger national debate, negotiators could not agree whether test scores are a valid way to assess teacher quality.

“There is no test anywhere that adequately connects K-12 student performance with what happened at a university 20 years before,” said Terry Hartle, senior vice president at the American Council on Education, which represents colleges and universities.