Lucy Meadows, who taught at an elementary school in Accrington in Lancashire, died earlier this week. By Friday, a petition demanding the firing of Richard Littlejohn had 3,000 signatures, the BBC reported.
Meadows, 32, started teaching at St. Mary Magdalen, a primary school operated by the Church of England, as Nathan Upton. A letter the head teacher, Karen Hardman, sent parents during the Christmas break was leaked to the news media.
"Mr. Upton has recently made a significant change in his life and will be transitioning to live as a woman," Hardman said.
A friend showed The Guardian emails from Meadows that described sneaking out the back door to go to work to avoid the media scrum at the front and staying at school for hours after students had left to outwait reporters and photographers.
Meadows filed a complaint with the Press Complaints Commission in January about a Littlejohn column headlined "He's not only in the wrong body ... he's in the wrong job" that suggested Meadows' change of gender would have a "devastating effect" on her students.
Those who have denounced Littlejohn include Alastair Campbell, who served as press secretary to Prime Minister Tony Blair.
A Mail spokesman accused Campbell of politicizing Meadows' death.
"It is regrettable that this tragic death should now be the subject of an orchestrated Twitterstorm, fanned by individuals -- including former Labor spin doctor Alastair Campbell -- with agendas to pursue," he said.
A vigil in front of the Mail offices in London was scheduled for Monday.