WTU President Nathan Saunders says Henderson was too closely aligned with former Chancellor Michelle Rhee.
According to the report, Saunders says he was concerned by what he called Henderson's "thin resume." He says when the union informed its members about a rally in support of the Wisconsin workers, Henderson directed principals not to approve any leave for the event -- a decision Saunders calls "vindictive".
But Henderson says it wasn't the rally she objected to. Rather, it was the timing -- 12:30 to 1:30 p.m. -- which is the middle of the school day.
"I fully support the union's right to and responsibility to stand with their brothers and sisters all across the country. But not on the time that I am paying them to teach children," she says.
The union also objects to Henderson being the only person considered for the position.