The fate of a giant Texas power company that has spent nearly a decade in financial distress lies in a potential battle between two billionaires.

On one side is Warren E. Buffett, who has agreed to pay $9 billion in cash for the utility operator, Energy Future Holdings. On the other is Paul E. Singer, the hedge fund mogul whose firm is the biggest creditor of Energy Future. Mr. Singer is exploring making its own takeover bid for the company, which has spent more than three years in bankruptcy proceedings.

A fight between the two would serve as the latest source of tumult for a company mired in financial and legal problems. And though Mr. Buffett is perhaps the most celebrated dealmaker in the world, Mr. Singer’s hedge fund, and perhaps Texas power regulators, threaten to stymie his latest takeover bid.

At the center of the brewing conflict is Energy Future, whose Oncor subsidiary is the biggest utility in Texas, with 10 million customers.