The largest rail union in the United States voted against a provisional September contract deal reached, meaning a strike is more likely to take place in the coming weeks, severely damaging the US economy.

Train and engine service members of the transportation divisions of the International Association of Sheet Metal, Air, Rail, and Transportation Workers (SMART-TD) voted with a slight majority to reject the deal.

Meanwhile, members of the Brotherhood of Locomotive Engineers and Trainmen (BLET) voted in favor of ratifying the agreement, with SMART-TD yardmasters voting in favor of ratifying their national agreement, the unions said on Monday.

Congress could be pressured to intervene and find a solution to the problem after the two largest unions representing train conductors and engineers could not agree on the agreement as the prospect of a strike ahead of the holiday season looms.

The National Carriers’ Conference Committee (NCCC) representing the nation's freight railroads in talks said the threat of an impending strike would require freight railroads and passenger carriers to "soon being to take responsible steps to safely secure the network in advance of any deadline."

In the meantime, the railroads did not at all signal any leniency in terms of holding talks, raising the prospect of Congress needing to intervene "to prevent disruption of the national rail system."

Union workers going head to head with their employers, demanding better working conditions and better pay, caused a disruption in the supply chain of fertilizers after hazardous materials, such as those used in fertilizer manufacturing, and disrupted US passenger railroad Amtrak service in September amid concerns about railroads stopping at any time.

Simultaneously, there is much distress in the US about vital shipments of food and fuel not reaching their destinations because of a strike.

Starting December 9, without intervention from Congress, SMART-TD will be allowed to strike, or the rail carriers would be allowed to lock out workers.

If any of the unions that voted against the deal organize a strike, BLET and other rail unions that ratified the agreement pledged to honor picket lines - the boundaries drawn up by striking workers.

The Biden administration helped avert a service cut-off by hosting last-minute contract talks in September at the Labor Department, which eventually led to the aforementioned deal.

The US Chamber of Commerce said last week that stepping in and preventing a potential rail disruption.

It is worth noting that a shutdown could freeze around 30% of US shipments by weight, stoking inflation, draining $2 billion out of the US economy daily, and causing many crises within the US transport sector, which would subsequently strike the US energy, agriculture, manufacturing, healthcare, and retail sectors.

The narrowly struck-down deal included a 24% compounded wage increase from 2929 through 2024, in addition to five $1,000 lump sum payments.

The unions have been highly vocal about the companies' sick leave and attendance policies, as well as the lack of paid sick days for short-term illnesses.