President Biden on Monday urged Congress to impose a labor agreement brokered by his administration on railroad companies and unions to avert a potentially crippling strike at the height of the holiday season.

Mr. Biden said would usually side with the right to strike but a railroad strike presented a special case.

“As a proud pro-labor president, I am reluctant to override the ratification procedures and the views of those who voted against the agreement. But in this case – where the economic impact of a shutdown would hurt millions of other working people and families – I believe Congress must use its powers to adopt this deal,” Mr. Biden said in a statement.

The Biden administration negotiated the deal in September, but four influential railroad workers’ unions rejected it, giving the two sides less than two weeks to avoid a strike before Dec. 9. strike deadline.

Union officials have warned a deal is increasingly unlikely and blasted the deal as unfair. They said they won’t approve the Biden-backed agreement because it lacks sick days and continues to penalize workers for taking sick time.

A strike could devastate the U.S. economy by disrupting the supply chain, halting passenger travel and delaying critical materials from reaching water treatment plants during the height of the holiday season.

Mr. Biden said that he didn’t want to lean on Congress to solve the crisis, but said he didn’t have a choice. He warned that a rail strike will “hurl this nation into a devastating rail freight shutdown.”

“My economic advisors report that as many as 765,000 Americans – many union workers themselves – could be put out of work in the first two weeks alone. Communities could lose access to chemicals necessary to ensure clean drinking water. Farms and ranches across the country could be unable to feed their livestock,” he said.