Teach for America, the education powerhouse that has sent thousands of handpicked college graduates to teach in some of the nation’s most troubled schools, is suddenly having recruitment problems.

For the second year in a row, applicants for the elite program have dropped, breaking a 15-year growth trend. Applications are down by about 10 percent from a year earlier on college campuses around the country as of the end of last month.

The group, which has sought to transform education in close alignment with the charter school movement, has advised schools that the size of its teacher corps this fall could be down by as much as a quarter and has closed two of its eight national summer training sites, in New York City and Los Angeles.

“I want the numbers to be higher, because the demand from districts is extremely high and we’re not going to meet it this year,” said Matt Kramer, a co-chief executive of Teach for America. But, he added, “it is not existentially concerning.”