Progress Energy and Duke Energy told their workers via e-mail that both power companies will offer voluntary buyouts this fall as North Carolina's largest electric utilities — which include Progress Energy Florida — prepare for their planned merger. Consider taking the buyouts, the company e-mails suggest, or face the possibility of being downsized later. Progress employs 11,000 in North Carolina, South Carolina and Florida, while Duke has 17,000 workers in North Carolina, South Carolina and the Midwest. Layoffs would likely begin in early 2012. A Progress Energy spokesman did not specify the size of possible job cuts but said any layoffs would focus on support staffers, such as those found in the legal departments, accounting, communications and media, IT and human resources. Progress Energy Florida, based in St. Petersburg, provides electricity to a broad swath of west-central Florida.