The Reverend Al Sharpton said yesterday that his decision to join a national group pushing for educational improvements has been criticized by a labor leader.

Rev. Sharpton said on his radio show that he received a telephone call from a union leader after his announcement that he is starting a new education group with school leaders who have called teachers unions obstacles to improvements.

“‘You can’t question teachers,'” Rev. Sharpton said the union leader told him. “I said, ‘What do you mean, I can’t question teachers? If teachers are not performing, they’ve got to be dealt with.'”

He did not name the leader.

A member of the new group, the Education Equality Project, said the president of the city teachers union, Randi Weingarten, complained loudly to Rev. Sharpton about the coalition.

Ms. Weingarten and Rev. Sharpton’s National Action Network denied that she was the union leader Rev. Sharpton mentioned.

“We haven’t had a cross word in years,” Ms. Weingarten said. She applauded Rev. Sharpton for working on education, she said, but added that she asked him this week why he instead hadn’t joined another new education coalition that she prefers, the Broader, Bolder Approach to Education.

An aide to Rev. Sharpton, Charlie King, said Rev. Sharpton misspoke by mentioning a “union leader.”

Mr. King said: “While Randi Weingarten has made clear that her preference is for this coalition not to take place, she has never said in a heated way or thrown any cross exchanges with either myself or Reverend Sharpton.”