A man walks past the headquarters of Puerto Rican power utility PREPA in San Juan, June 30, 2015. Reuters/Alvin Baez-Hernandez

A deal that would have restructured about $9 billion in debt issued by Puerto Rico's electric utility, seen as a key in helping the embattled U.S. commonwealth get its finances back in order, fell through early Saturday after the island's lawmakers missed a midnight deadline to vote on a piece of legislation that was part of the agreement, and the power utility and its creditors failed to agree on terms for an extension, the Financial Times reported.

The legislation would have added a surcharge on the consumer accounts of the Puerto Rico Electric Power Authority (PREPA) that would go directly toward debt payments. After Puerto Rico's lawmakers did not approve it in time, the two sides failed to come to an agreement to extend the deadline.

"We are disappointed that the ... group did not grant our requested extension," Lisa Donahue, PREPA's chief restructuring officer, said in a statement provided to Reuters. "PREPA remains willing to continue discussions with the Ad Hoc Group and other stakeholders."

The group of bondholders, which include money management giants Franklin Templeton and Oppenheimer, issued a statement calling PREPA's decision "extremely disappointing and perplexing."

The island's creditors and politicians are awaiting a ruling from the U.S. Supreme Court, which is set to hear an appeal this year from Puerto Rico that would allow it to push the power utility into bankruptcy. Puerto Rico is bleeding both people and its cash reserves after years of economic decline and has a 45 percent poverty rate. The governor of Puerto Rico, Alejandro Garcia Padilla, has called it "unpayable."