Spirit Airlines has almost finished refunding customers for flights abruptly canceled over the weekend as the company folded.

The budget airline left thousands of customers and staff stranded after deciding on Saturday to pull the plug on a business that was struggling for years, before a surge in the price of jet fuel blew a new hole in its budget.

Spirit had scheduled about 4,000 flights through 15 May, according to Reuters.

The airline has not made a profit since 2019, according to CNBC. The company attempted unsuccessfully to restructure in recent years after two bankruptcy filings. The sharp rise in the cost of oil resulting from the US-Israeli war on Iran dealt the airline its death blow, Spirit said in a statement.

“Unfortunately, despite the company’s best efforts, the recent material increase in oil prices and other pressures on the business have significantly impacted Spirit’s financial outlook,” the statement reads. “With no additional funding available to the company, Spirit had no choice but to begin this wind-down.”

The US transportation secretary, Sean Duffy, however, cast the blame for the airline’s failure on the Joe Biden administration in comments to the media on Saturday. The justice department under Biden blocked a proposed merger that would have joined Spirit and JetBlue.

“Many at the time said this was a disaster, this merger should have been allowed,” Duffy said. “And this today would indicate this is not better for travelers, this is not better for pricing, this is not better for competition – actually it’s worse.”

Duffy urged Spirit customers to stay home.

“If you have a flight scheduled with Spirit Airlines, don’t show up at the airport – there will be no one here to assist you,” Duffy said. “What Spirit Airlines is now going to do is go through an orderly liquidation process. We’ll see how that goes through the course of the next couple of days.”

Conservative critics, including Duffy, drew attention to comments from Elizabeth Warren, a Democratic senator from Massachusetts, praising the Biden administration’s blocking of the merger back in 2024. Warren said at the time that the merger would have led to “fewer flights and higher fares”.

In response to the criticism, Warren tweeted on X that Spirit collapsed over spiking oil prices, adding that the “JetBlue merger failed because a judge, appointed by Ronald Reagan, said the deal was illegal”.

“Republicans are desperate to shift blame from higher costs hitting families,” Warren tweeted.