ALLEN REEDRALEIGH, N.C. (AP) â¿¿ Opponents of the creation of the nation's largest electric utility have one more chance to plead their case before energy regulators. Charlotte-based Duke Energy Corp. has until July 8 to complete its takeover of Raleigh-based Progress Energy Inc. under their current agreement started in January of 2011. The North Carolina Utilities Commission will hold a hearing Monday in Raleigh at the behest of environmental nonprofit NC Waste Awareness and Reduction Network. NC WARN is trying to put the brakes on the $23.4 billion deal that would span six states, employ nearly 30,000 workers, serve more than 7 million accounts and have more than $100 billion in assets. The nonprofit argues the marriage between the energy giants will increase prices that customers pay. They say the companies have hid millions of dollars in costs that will raise utility rates. "Electric rates are a big chunk of people's monthly budgets for families and small business and others," said Jim Warren, executive director of NC WARN. "When we talk about millions of dollars of risks that could be placed on rate payers, that means costs would rise even more." The energy companies maintain the opposite â¿¿ that the coupling will save $650 million by combining forces, and that the savings will trickle down to customers. "NC WARN has had many months to access this information as other interveners in procedure have done," said Progress Energy spokesman Mike Hughes. "It's somewhat odd that suddenly there is a desire to do this when there is a time constraint." So far, the energy companies' answers have been sufficient for clearing multiple regulatory hurdles. The most significant came on June 8, when the Federal Energy Regulatory Commission gave its blessing after twice rejecting the merger because of concerns it would reduce competition for wholesale electricity in the Carolinas. The deal received endorsements by the U.S. Department of Justice, U.S. Nuclear Regulatory Commission, the Federal Communications Commission, the Kentucky Public Service Commission and others. The Public Service Commission of South Carolina is also reviewing the merger, but its blessing is not required.