New York CNN Business  — 

About 8,000 grocery store workers at 77 King Soopers and City Markets stores in the Denver area are on strike after the union rejected what the company described as its best and final offer to replace a recently expired contract.

The strike started Wednesday morning against the stores, which are part of Kroger (KR), the nation’s largest stand-alone grocery retailer.

The number of members of the United Food & Commercial Workers union who are on strike make it the nation’s second largest strike of the last two years, behind only a five-week work stoppage by 10,000 auto workers at John Deere & Co. that ended in November.

The rank-and-file workers at King Soopers and City Markets voted ovewhelmingly last week to authorize the strike, according to the union, which did not hold a separate vote to consider the company’s final offer. The union said that offer would have created a new subclass of gig workers, which it claimed would be used to reduce work hours and drain the company’s health fund for long-term employees. It also did not address worker concerns about Covid safety measures to protect both employees and customers, the union added.

“The company’s ‘last, best, and final’ offer, in many ways, is worse than its previous offers,” said Kim Cordova, president of the local unit of the striking union. “Clearly, King Soopers/City Market will not voluntarily meet the needs of our workers, despite our repeated pleas for the company to listen to the voices of our members. We strike because it has become clear this is the only way to get what is fair, just, and equitable for the grocery workers who have risked their lives every day just by showing up to work during the pandemic.”

The company said the stores would remain open during the strike, and it criticized the union for not putting the latest contract offer to a vote by the rank and file. The latest offer would raise starting pay to $16 an hour, the company said, and checkers who are currently paid $19.51 an hour would get raises totaling $3.10 an hour, or nearly 16%, over the three-year life of the contract. Employees with 10 or more years of service also would get a $4,000 signing bonus, and less senior workers would get $2,000, according to the company.

The union “is putting politics before people and preventing us from putting more money in our associates’ pockets,” said Joe Kelley, president of King Soopers and City Market. “Creating more disruption for our associates, their families, and Coloradans rather than negotiating for a peaceful resolution is irresponsible and undemocratic.”

But with a very tight labor market, a record numbers of unfilled job openings and many employers reporting difficulty finding the workers they need, workers are flexing their muscle in collective bargaining talks, demanding deals better than what they may have accepted in the past.

Many rank and file union members in other recent contract negotiations rejected tentative labor deals that management described as “best possible” offers.

That’s what happened at John Deere (DE) last year when 10,000 striking employees rejected one tentative agreement, which initiated the strike, and then voted no to a second pending agreement before finally ratifying a third deal and returning to work in late November.

There were also multiple no votes by 1,400 workers at Kellogg (K) before they voted to end an 11-week strike just after Christmas. And even in some cases where tentative agreements do pass, they are approved by the narrowest of margins. Members of a union representing 63,000 film and television production workers voted only 50.3% in favor of a deal in November that narrowly averted a massive strike at major studios.

The retail sector has very little in the way of union representation. US Labor Department stats from 2020 show that only 783,000 retail employees — or 5.1% — are represented by a union, even less than the 7.2% of private sector workers who are unionized. Grocery stores are far more likely than other retailers to have union representation.

Sen. Elizabeth Warren criticized Kroger and voiced support for the strikers in a tweet Thursday.

“Huge grocery chains like Kroger have made billions by jacking up consumer prices. And they’re using those profits to reward executives instead of raising wages so workers can make ends meet,” Warren said. “I stand with Kroger workers in their fight for a fair contract.”