(Edward M. Pio Roda/AP)

The presidential campaigns and the Commission on Presidential Debates are trying to quiet CNN’s Candy Crowley, even before she takes the stage at Tuesday night at Hofstra University to moderate the second presidential debate. As Time magazine’s Mark Halperin reported last night, the campaigns signed a memorandum of understanding with the commission this month in which they agreed that Crowley would have a limited role in the proceedings.

The key consideration in the alleged fracas is the format of the Hofstra clash. It’s a town hall, in which citizens get to ask the candidates questions — the people’s debate, that is. That format builds in automatic tension with a moderator like Crowley, who’s used to running her own shows. Or any self-respecting journalist, for that matter.

On CNN’s air, Crowley said this about her role: “Once the table is kind of set by the town-hall questioner, there is then time for me to say, ‘Hey, wait a second, what about X, Y, Z?’”

Sounds reasonable, no?

Except it doesn’t to the campaigns and the commission. According to Halperin’s report, here’s how the conflict breaks down:

According to the town-hall format language in the agreement, after each audience question and both two-minute responses from the candidates, Obama and Romney are expected to have an additional discussion facilitated by Crowley. Yet her participation is meant to be otherwise limited. As stated in the document: “In managing the two-minute comment periods, the moderator will not rephrase the question or open a new topic … The moderator will not ask follow-up questions or comment on either the questions asked by the audience or the answers of the candidates during the debate or otherwise intervene in the debate except to acknowledge the questioners from the audience or enforce the time limits, and invite candidate comments during the two-minute response period.”

Why not just put an addendum in there: In addition to “inviting” comments, the moderator will make sure that the candidates’ water glasses remain full. There’s “no evidence” that Crowley agree to the terms of the memorandum, according to Halperin. Good for her.