Cooper's office, which said 280 people wrote him letters objecting to the rate increase, announced that Cooper's Consumer Protection Division has intervened in the rate case.
In addition to objections over the proposed hike, the company is facing several other challenges right now, including resistance from regulators to Duke Energy merging with Progress Energy and increased expenses from a plant it's building in Indiana.
Duke Energy announced its third-quarter earnings on Thursday, raking in $472 million in profits.
University of North Carolina utilities expert and professor of economics Dr. Peter Schwarz said Duke Energy could be facing some tough times ahead, especially with the growing pushback.
Eyewitness News asked Duke Energy's Director of External Relations Tom Williams how confident company officials currently feel.
"We feel very confident. We've had a very good quarter," Williams said.
Because of its continued profits, some people said it's hard to understand why the company is requesting such a large rate increase.
"I think it's awful," Shawn Easter said. "A lot of us can't afford to pay our bills as it is."
For customers like Easter, the increase would mean a 17 percent increase.
This week, the state consumer advocacy agency, known as the Public Staff of the N.C. Utilities Commission, suggested an increase of just 4.8 percent.
"They're running into some challenging timing on the things they're trying to do," Dr. Schwarz said.
He said it's clear resistance is building.
"Consumers are right now more active in terms of pushing back in general," he said. "Ultimately, I think it's pretty clear that it may well not be as large as Duke asked for."
Consumer advocates there claim that "Duke grossly mismanaged the project and attempted to conceal mistakes."
Williams said Duke Energy has hired its own independent consultant. He said there is no mismanagement.
"We're certainly telling our case to the commission in Indiana and we're confident we'll come out just fine with that," he said
Duke Energy officials agree that there are challenges but they are not backing down. They said they need the increase to pay for infrastructure improvements and new power plants.
The decision is up to North Carolina Utilities Commission, which starts hearings on the case Nov. 28.
Previous Stories: November 1, 2011: Duke, Progress want new hearing on merger October 17, 2011: Duke Energy president discusses controversy surrounding proposed rate hike October 14, 2011: Channel 9's getting answers on Duke Energy's rate increase October 12, 2011: State group will decide on Duke's proposed rate hike October 12, 2011: Dozens protest Duke Energy rate hike