More than a dozen major U.S. retailers were due to open on Thanksgiving Day — a break with tradition that gives shoppers a jump on the holiday shopping season but has drawn protests from workers' groups.

The day after Thanksgiving, known as Black Friday, has long been considered the official start of the holiday buying season. It’s typically the biggest shopping day of the year.

But in the past few years, retailers have pushed opening times into Thanksgiving night in a bid to grab early customers. They’ve also pushed up discounting that used to be reserved for Black Friday into early November, which has led retail experts to question whether pre-Thanksgiving sales will steal some of Black Friday’s thunder.

The decision by some retail giants to open on Thanksgiving has been greeted by alarm by those who resent the intrusion of consumerism on a day that has traditionally been about bringing family together. Workers planned petitions and protests around the country to coincide with early opening hours.

Walmarts have been the biggest target for protests against holiday hours. Most of the stores are open 24 hours, but the retailer is starting its sales events at 6 p.m. on Thursday, two hours earlier than last year.

The issue is part of a broader campaign against the company’s treatment of workers that is being waged by a union-backed group called OUR Walmart, which includes former and current workers. The group is staging demonstrations and walkouts at hundreds of stores around the country on Friday.

Anthony Goytia, a Walmart employee in Duarte, Calif., told Al Jazeera’s Peter Moskowitz that he plans to protest low wages on Black Friday. A father of four, Goytia said that last year he made $12,000.

The National Labor Relations Board (NLRB), the federal body charged with protecting employee rights, told Al Jazeera on Nov. 18 that it had “found merit” in a number of labor-rights complaints against the retail giant — including allegations that Walmart unlawfully penalized employees for participating or being suspected of wanting to participate in demonstrations at store locations in 13 states.

Brooke Buchanan, a Walmart spokeswoman, told The Associated Press the discounter has received “really good feedback” from employees about working on Thanksgiving.

Walmart said workers get additional pay for working on the holiday. The company planned to serve meals at the stores and is giving employees a 25 percent discount on a single purchase.

But Walmart worker Cindy Murray, 57, shrugged off the perks and said she won’t be able to sit down for a Thanksgiving meal with her family until after her nine-hour shift ends at 4 p.m. She says the company can’t put a price on the holiday.

“If they want to do something for us, they will go back to the old tradition,” she said.

Walmart is not alone in taking heat from those against Thanksgiving Day trading. Dozens of petitions on Change.org are demanding that retailers “save Thanksgiving” and push their store hours back to Friday. Some are calling for shoppers to boycott major retailers that open their doors on Thursday.

This year Kmart stores opened their doors as early as 6 a.m. Thursday, with plans to stay open until 11 p.m. Friday. Toys R Us opened at 5 p.m. on Thanksgiving until 10 p.m. on Black Friday.

Meanwhile, a handful of franchise owners defied corporate orders by keeping their stores closed for the holiday.

“It bothers me that this country is allowing them (companies) to dictate time away from our families, Holly Cassiano, who refused to open her Sears franchise in Plymouth, N.H., told CNN.

On Wednesday a Pizza Hut store manager was offered his job back after the fast-food firm relented to an online campaign mounted after he was seemingly let go after refusing to make staff work on Thanksgiving.

But negative publicity isn’t the only effect of Thanksgiving trading. Opening early is likely to take a chunk out of Black Friday profits for retailers. Sales on Thanksgiving in 2012 amounted to $810 million, an increase of 55 percent from the previous year, according to Chicago research firm ShopperTrak. But business dropped 1.8 percent, to $11.2 billion, on Black Friday, though it still was the biggest shopping day last year.

Stores are trying to attract shoppers to buy in an economy that’s still challenging. While the job and housing markets are improving, that hasn’t yet translated into sustained spending increases among most shoppers.

Overall, the National Retail Federation expects retail sales for the last two months of the year to be up 3.9 percent, to $602.1 billion, compared with 2012. That’s higher than last year's 3.5 percent growth but below the 6 percent pace seen before the recession.

But analysts expect sales to be generated at the expense of profits, as retailers will likely have to do more discounting to get people into stores. More than two dozen companies, including Kohl’s and Walmart, have already lowered their profit outlooks for the year.

Retailers’ strategy is to lure shoppers in early and often, including on Thanksgiving. But the stores face challenges in doing that.

Al Jazeera and The Associated Press