OpenAI is close to leasing a $500 billion data center in southern Ohio that could be among the largest of the artificial intelligence boom, according to three people familiar with the project.

OpenAI is in separate talks with the chipmaking giant Nvidia for a $250 billion financial backstop for the project, said the three people, who spoke on the condition of anonymity because they were not authorized to discuss it.

The U.S. government, which is helping to provide the electrical power for the project, is still talking to other potential tenants, and the deal will not be final until Commerce Secretary Howard Lutnick agrees to it, one of the people said.

But the Japanese conglomerate SoftBank, an OpenAI investor that is leading the development of the data center, and government officials are leaning toward OpenAI as the main tenant because Nvidia has added financial muscle to the A.I. company’s proposal, the three people said.

Microsoft, Google and possibly other companies have also submitted bids to use the data center, the people said. The center, financed in part through a trade deal with Japan, will be backed by 10 gigawatts of electricity, which is enough to power millions of households.

The financing for the Ohio project is indicative of the elaborate deals that have helped fuel the A.I. boom over the past several years. Through unusual and creative arrangements with chipmakers, cloud-computing companies and governments across the globe, start-ups like OpenAI and Anthropic are tapping into huge amounts of computing power they could not afford on their own.