DES MOINES, JAN. 16 -- Democratic presidential candidate Bruce Babbitt apologized today for a joke he said was "insensitive" to the parents of two missing Des Moines Register newspaper boys.

During a debate of Democratic candidates Friday night, former Arizona governor Babbitt joked that the campaign of Sen. Albert Gore Jr. (D-Tenn.) was so invisible in Iowa that he expected to see Gore's picture on a milk carton.

"Al, it's good to see you back," Babbitt said. "You know, I thought they might start putting your picture on milk cartons."

The joke fell flat to many in Iowa, where the disappearances of two Des Moines Register delivery boys in 1982 and 1984 set off a national network to help find missing children by placing their pictures on milk cartons. The debate was sponsored by the Register.

Noreen Gosch, whose son, Johnny, disappeared in 1982, said Babbitt's remark angered her. "My husband and I were just sickened to hear it," Gosch said. Babbitt said he did not realize how sensitive the subject was in Iowa and said the off-the-cuff remark "was totally insensitive."

"I have placed a call to Mrs. Gosch, and I will offer her my full apologies," Babbitt told United Press International. "It was a spontaneous kind of thing, and I didn't realize what I was saying."