“We would talk about impacts of different options in the briefing,” Ms. Cleland-Hamnett wrote in a March 7 email. The email raised the possibility of a meeting with Mr. Pruitt to discuss the pesticide, a decision that the E.P.A.’s political staff had called a “hot” regulatory item, given a court-ordered deadline of late March to rule on the petition.

The next day, Ryan Jackson, Mr. Pruitt’s chief of staff, wrote to another political appointee that he had “scared” the agency’s career staff, suggesting that he had made clear the direction that the political staff wanted to go — and given the career staff explicit verbal orders to prepare documents explaining why the agency had shifted its position.

“I think I did scare them or surprise them,” Mr. Jackson wrote to Samantha Dravis, Mr. Pruitt’s political appointee to oversee E.P.A. policy. “They are getting us information for Friday but they know where this is headed and they are documenting it well.”

As the draft of the order rejecting the ban of the petition was being written, political staff at the E.P.A. continued to organize meetings with agriculture industry officials. An email on March 10 said: “Basic info for meeting. Purpose is to reset relationship with ag leaders.”

When Ms. Cleland-Hamnett wrote back to the political appointees on March 16 to provide a draft of the order rejecting the ban of the pesticide, she told her bosses that “I think this version will allow you to see how we’re describing the basis for the denial.”

The emails indicate E.P.A. officials closely coordinated their decision on chlorpyrifos with the White House and the Department of Agriculture, which is more closely linked with the agriculture industry and had questioned the justification for the ban.

On March 29, as the E.P.A. was about to publicly announce Mr. Pruitt’s decision to forego the ban, an E.P.A. political employee asked in an email, “Did you run this by Ray Starling at the White House?” referring to the special assistant to the president for agriculture, trade and food assistance.