The cost of building the only nuclear power plant under construction in the U.S. has ballooned to more than $25 billion, but chief owner Southern Co. said it isn’t ready to throw in the towel on the project.

The company released the new cost estimate for Georgia’s Vogtle Electric Generating Plant on Wednesday, adding that it expects completion of the plant, which has already seen years of delays and rising costs, to be delayed by another 18 months until February 2021 at the earliest.

The price would be split between Southern, three regional power companies, which are partners in the project, and Toshiba Corp., whose subsidiary, Westinghouse Electric Corp., went bankrupt earlier this year while building the plant.

The disclosure from Southern comes two days after Scana Corp. pulled the plug on a similar nuclear plant in South Carolina. It also had years of delays and cost increases that put final completion of that facility above $25 billion as well.

Southern Chairman and Chief Executive Thomas A. Fanning said during a conference call with analysts that he wasn’t ready to give up on the Vogtle plant.