The US House of Representatives moved urgently to head off the looming nationwide rail strike on Wednesday, passing a bill that would bind companies and workers to a proposed settlement.
The proposed settlement was reached in September but rejected by some of the unions involved.
The measure passed by a vote of 290-137 and now heads to the Senate. If approved there, it will be signed by President Joe Biden, who urged the Senate to act swiftly.
“Without the certainty of a final vote to avoid a shutdown this week, railroads will begin to halt the movement of critical materials like chemicals to clean our drinking water as soon as this weekend,” Mr Biden said.
“Let me say that again: Without action this week, disruptions to our auto supply chains, our ability to move food to tables and our ability to remove hazardous waste from gasoline refineries will begin.”
Business groups including the US Chamber of Commerce and the American Farm Bureau Federation have warned that halting rail service would cause a devastating two billion dollar (£1.7b) per day hit to the economy.
The bill would impose a compromise labour agreement brokered by the Biden administration that was ultimately voted down by four of the 12 unions representing roughly 115,000 employees at large freight railroads.
The unions have threatened to strike if an agreement cannot be reached before a December 9 deadline.
Lawmakers from both parties expressed reservations about overriding the negotiations.
The intervention was particularly difficult for Democratic lawmakers who have traditionally sought to align themselves with the politically powerful labour unions that criticised Mr Biden’s move to intervene in the contract dispute and block a strike.
House Speaker Nancy Pelosi responded to that concern by adding a second vote on Wednesday that would add seven days of paid sick leave per year for rail workers covered under the agreement.
However, it will take effect only if the Senate passes both measures.
The House passed the sick leave measure as well, but by a much narrower margin, 221-207, as Republicans overwhelmingly opposed it, indicating that prospects for passage of the add-on are slim in the evenly divided Senate.