Rick Wilking/Reuters

Hostess Brands announced on Tuesday night that despite the help of a mediator, it had failed to reach a new labor agreement with the bakery workers union — and union officials said the company had indicated it would proceed with plans to liquidate.

“It’s over,” said David Durkee, secretary-treasurer of the Bakery, Confectionery, Tobacco Workers and Grain Millers International Union.

Hostess, an 82-year-old company, said that it would have no further comment until a hearing scheduled for 11 a.m. Wednesday before Judge Robert D. Drain of the Federal Bankruptcy Court for the Southern District of New York. At a hearing on Monday, Judge Drain, eager to save the 18,500 jobs at Hostess, pressed the two sides to meet with a mediator, hoping the long-feuding company and union could narrow their differences.

Tuesday’s announcement came four days after Hostess announced that it would wind down its operations, a move precipitated by a bakery workers’ strike that began on Nov. 9 at two-thirds of the company’s 33 bakeries.

Ever since Hostess filed for bankruptcy last January, it has insisted that its labor costs were unsustainable and that it needed to cut its wage, health and pension costs to continue operating. But the bakery workers’ union balked, asserting that Hostess was badly managed and that the company would most likely face liquidation again.

Hostess had reached a settlement in September with the Teamsters, which, with 6,700 workers at Hostess, was far more willing to cooperate to help the company survive. The Teamsters, which also attacked the company for mismanagement, agreed to an immediate 8 percent pay cut, a suspension of the company’s pension payments into 2015 and a 17 percent cut in contributions for health coverage.

But Frank Hurt, the president of the bakery workers’ union with 5,600 members at Hostess, repeatedly said he would not entertain such steep concessions, saying they would drag down wages and benefits throughout the industry, without guaranteeing Hostess’s survival. Mr. Hurt said that the company was brought down by private equity firms, which he decried as “vulture capitalists,” criticizing them for not investing more to modernize Hostess’s bakeries and product offerings.

Earlier this year, Hostess had more than $860 million in debt. In fiscal 2012, it reported revenue of $2.5 billion and a net loss of $1.1 billion.

Those involved in the talks with the mediator declined to talk, largely because Judge Drain had ordered them not to discuss what happened inside the mediation, which was held in the offices of the company’s lawyers. One bankruptcy expert said that Judge Drain, known for being assertive, might reach for some new way for the company to survive — although the bakery workers’ strike hurt the beleaguered company’s future by curtailing the flow of Hostess goods to thousands of grocery stores.

If Hostess proceeds to liquidation, some of its competitors might seek deals for its most popular brands, especially Twinkies. One possible buyer is Flowers Foods, which recently expanded its borrowing capacity. Grupo Bimbo, the world’s largest bread-baking company, is also considered a potential purchaser.

Financial investors like Sun Capital Partners and Metropoulos & Company have also voiced interest in a deal with Hostess.