"I think there's a bias, a racial bias," Peggy Cochran, former executive director of the Missouri Education Association, said in The Hill. "For some, there's a bias for [Obama's] youth."

Despite the leadership of senior AFL-CIO officials, a significant number of members in the middle and lower ranks of unions that endorsed Clinton have been slow to back Obama, said a senior union official who spoke on condition of anonymity.

"There's been some reluctance on the part of a couple of unions," said the official, who cited unionized teachers and the International Association of Machinists and Aerospace Workers.

Not exactly a glowing assessment of America's teachers and one we, frankly, find hard to believe.  But it's their leaders saying it, so it must be true.

Karen Ackerman, political director for the AFL-CIO, acknowledged that Obama's race is an important factor for some union members.

"This race is very complicated because there is an African-American candidate for president," said Ackerman. "We feel there is a racial component for some union members, but we're confident we can overcome that."