Legislation to force railroad workers to accept a compromise labor contract negotiated by the Biden administration would be an 11th hour sellout, according to union leaders who are infuriated with actions taken by the self-described “most pro-union president” in history. 

“The ‘most labor-friendly president in history’ has proven that he and the Democratic Party are not the friends of labor they have touted themselves to be. These wolves in sheep’s clothing have for decades been in bed with corporate America and have allowed them to continue chipping away at the American middle class and organized labor,” the Railroad Workers Union co-chairman, Gabe Christenson, who is also a conductor, said. 

“This is a legacy defining moment for Joe Biden. He is going down as one of the biggest disappointments in labor history,” the RWU tweeted on Tuesday.

Lawmakers on both sides of the aisle are also displeased they are being forced to intervene in an internal union dispute. Before the election, President Biden claimed the deal was done, and “now we find ourselves in the last hours asking us to rush a bill to the floor,” the House minority leader, Kevin McCarthy, said. 

Congress is empowered by the Railway Labor Act to step in and force rail workers back to the tracks. The request by Mr. Biden for congressional intervention came after four of the 12 unions in the negotiation rejected the Presidential Emergency Board’s proposal, crafted in September.

That deal gives 115,000 rail workers a 24 percent raise over five years and other concessions, as well as additional personal leave days. Workers insisted on four guaranteed sick days each year, down from the 15 they had asked for in earlier negotiations. 

Eight of the 12 unions involved in the negotiations have ratified the contract. The largest of the unions, The Smart Transportation Division, was split. Smart-TD yard workers supported the deal, but 50.87 percent of its conductors voted to reject the offer. If any one of the 12 unions refuses to ratify, the rest have agreed not to cross a potential picket line.

If Congress steps in, the workers won’t have a choice. Speaker Pelosi said that the legislation she will introduce in the House as early as Wednesday will come to the floor exactly as the emergency board recommended — much to the dismay of the unions’ rank-and-file employees.

“I don’t like going against the ability of unions to strike, but weighing the equities, we must avoid a strike. Jobs will be lost. Even union jobs will be lost,” Mrs. Pelosi said after a White House meeting on Tuesday.

Later, however, the New Jersey Democrat who is chairman of the House subcommittee on railroads, pipelines, and hazardous materials, Representative Donald Payne, told the Sun he will introduce legislation to guarantee paid sick leave for rail workers. He did not say whether it would be an amendment to the current bill or separate legislation. Senators Sanders and Sinema also told reporters they want a sick leave amendment.

Mr. Biden has asked that lawmakers not make any changes that “would risk delay and a debilitating shutdown. The agreement was reached in good faith by both sides.”

A railroad strike would have dire repercussions across America. A screeching halt would cripple every corner of a struggling economy — from energy, food, and manufacturing to holiday travel and daily commutes. Because railroads transport 162,000 barrels of crude oil a day, the shock could cause an immediate spike in gas prices. 

Unions would have to ratify the deal by December 9 to avert a strike, but the true drop-dead date for the economy is Saturday. If a strike occurs, hazardous materials like chemicals, diesel, and other fuel transport will stop first.

Meanwhile, the proposed bill does not appear to be gaining traction among progressive Democrats or populist GOP lawmakers, both of whom have cast themselves as defenders of the working class. 

“Last year, the rail industry made a record-breaking $20 billion in profits. They can afford to give their workers paid sick leave,” Representative Rashida Tlaib, a Michigan Democrat who is vice chairwoman of the Congressional Progressive Caucus, tweeted. “The rail industry must put the quality of life of their employees over profits. I stand with rail workers.”

Senator Rubio, the Republican of Florida, said he won’t impose a deal on rail workers without their support. “The railways and workers should go back and negotiate a deal that the workers, not just the union bosses, will accept,” he tweeted.