Walmart, Toys R Us and Sears are opening their doors at 8 p.m. Thursday — just as dinner tables are being cleared in many homes. Target will follow suit at 9 p.m., enticing shoppers out of their homes during the final football game of the day.

Not everybody is happy about it, but retailers are scrambling to make the most of what is expected to be a mediocre shopping season — even if it means cutting into a holiday.

“There’s a segment of the population who wants to drop their drumstick and immediately pick up a door-buster,” said Brian Hanover, a spokesman for Sears. “Our customers kept telling us they wanted more flexible Black Friday shopping hours.”

Last year, when stores opened as early as 9 p.m. on Thanksgiving, it sparked protests from workers and shoppers who worried that there soon wouldn’t be any holiday left. This year, as retailers start even earlier, similar protests are under way: Target employees have started a petition to “save Thanksgiving,” and Walmart workers say they are gearing up for protests on Black Friday.

“It’s ridiculous,” said Anthony Hardwick, a former Target employee who led protest efforts last year. “We’re getting rid of Thanksgiving dinner, and for what? For a $300 flat-screen TV?”

But retailers think they have found a new pocket of holiday shoppers — those who aren’t eager to wake up early Friday for the traditional discounts but are willing to cut short Thanksgiving dessert.

Perhaps the earliest door-busters of the season will begin at 6 a.m. on Thanksgiving, when Kmart will begin selling high-definition plasma TVs for $199.99. The retailer has stayed open on the holiday for the past 21 years but only recently began offering Black Friday discounts a day early.

“Over the years, the day has become bigger and more important,” said Andy Stein, Kmart’s interim chief marketing officer. “We’ve evolved from being open for last-minute Thanksgiving dinner needs like tin foil and gravy to doing door-busters at 6 a.m.”

Retailers say last year’s earlier openings drew a younger crowd of shoppers who prefer to stay up late rather than wake up early to snag deep discounts. Nearly one-fourth of consumers who shopped during the holiday weekend were at stores at midnight on Black Friday, up from 3 percent in 2009, according to the National Retail Federation.

“Stores are tapping into something that is very real — there is demand for this,” said Adam Hanft, a brand strategist for Hanft Projects in New York. “The reality is, people start to get cabin fever after awhile. They’re fighting about politics. They want to get out and do something.”

The intrusion into Thanksgiving comes as retailers try to offset yet another expected year of tepid holiday sales. Overall holiday sales, which typically account for 40 percent of retailers’ annual revenue, are forecast to grow 4.1 percent this year, down from 5.6 percent a year ago, according to the National Retail Federation.

In their quest for sales, stores are looking for new ways to bring in consumers. And they won’t be satisfied with just one visit.

Walmart and Target are staggering their Black Friday promotions, launching sales of coveted products such as iPads at specific times in hopes that shoppers will return again and again to get the lowest prices. Walmart will release different deals at 8 p.m. and 10 p.m. on Thanksgiving, and again at 5 a.m. on Black Friday. Target, Kmart and Sears have similar plans, which could cause big crowd problems.

“If customers want to go home, we’d love to have them come back at 5 a.m. the next morning,” said Duncan Mac Naughton, Walmart’s chief merchandising and marketing officer.

Even so, analysts say earlier opening times might not translate into higher revenue. The sales that stores rack up on Thanksgiving could eat into purchases that typically take place on Black Friday and the rest of the weekend.

“I really don’t think it means very much,” said Maggie Gilliam of the New York-based research firm Gilliam & Co. “The earlier you get people in, the more likely they are to keep spending, but frankly, I wouldn’t read too much into it.”

But as long as demand for Thanksgiving Day shopping remains high, retailers say they will continue to open earlier.

“Shoppers have shown us that they love wrapping up their Thanksgiving meals, grabbing their coats and going shopping,” said Kathy Grannis, a spokeswoman for the National Retail Federation. “There are millions of people who do want to shop on Thanksgiving Day.”