As retailers prepare for the traditional start of the holiday season this coming week, some of the nation's biggest chains plan to pre-empt Black Friday with shopping hours and special events on Thanksgiving Day — a move that has triggered a spate of online protests.

Toys "R" Us will open stores at 9 p.m. and Walmart will follow at 10 p.m., meaning that shoppers may be lining up for bargains soon after their turkey dinners. Target, Best Buy and Kohl's are shifting from their usual pre-dawn Friday openings, welcoming shoppers at midnight. And a growing number of malls and mall stores are promoting openings at midnight or earlier.

Some retailers also will usher in the season with events designed to attract shoppers before the sales begin. Best Buy is offering free screenings of the final Harry Potter movie at some stores. Bass Pro Shops, which has a store at Arundel Mills, is inviting shoppers to sit around bonfires, sip hot chocolate and compete for prizes, including a leased Toyota Camry.

For retailers, it's all about getting to that crucial holiday shopper first, in a year when a troubled economy means any misstep will be costly, experts say. And this year more than ever, the lines between Thanksgiving and the post-holiday shopping period appear to have permanently blurred.

"The economic climate clearly is not wonderful," said Barry Berman, a marketing and retail professor at Hofstra University. "And retailers are very concerned about inventories, about meeting sales goals, and very much concerned about having markdowns late in the season."

So retailers are trying to broaden Black Friday opportunities, and for most people, "9 p.m. is more rational than 4 in the morning," Berman said. But he also worries that such trends have bigger implications. "Too many of the national holidays have lost their significance."

Retailers say they're simply satisfying consumer demand, which this year will mean catering to as many as 152 million Americans who plan to shop over the holiday weekend, according to an industry survey released last week. That includes 77 million people who say they will hit the stores only if bargains make it worthwhile.

"Retailers continue to open earlier and earlier every year, and consumers continue to show up," said Casey Chroust, an executive vice president of the Retail Industry Leaders Association. "Consumers vote with their feet and their wallets. If they weren't showing up, retailers wouldn't do this. If they can get that shopper in their store first, they're more likely to spend money."

Walmart, the nation's biggest retail chain, said the Thanksgiving hours are a response to consumer demand. "Our customers told us they would rather stay up late to shop than get up early," chief merchandising officer Duncan Mac Naughton said in a statement.

Analysts say it's too soon to tell how successful the Thanksgiving sales campaigns will be. About a third of consumers expect to shop on Black Friday, a slight increase over last year, according to an analysis by the International Council of Shopping Centers and Goldman Sachs. But only 16 percent said they would take advantage of the limited Thanksgiving Day hours.

It's also unclear whether growing opposition to the ever-earlier sales will dampen shoppers' enthusiasm.

While anti-Black Friday movements have sprung up in the past, a new wave has gained momentum over the past week. Some retail employees, consumers and even store competitors are calling the Thanksgiving hours and midnight openings unnecessary and too burdensome for workers.

Several dozen online petitions on the change.org website have attracted tens of thousands of supporters. Meanwhile, some retailers, including Sears, have sought to distance themselves from competitors.

"There seems to be a pack mentality right now with retailers following each other," Tom Aiello, divisional vice president tor Sears Holdings, said in a statement, adding that its customers have indicated "they didn't want to be forced to get up at midnight to get the best deals."

Sears will open at 4 a.m. Friday, as will JCPenney.

Abe Bonowitz of Cheverly is among the more than 180,000 people nationally who signed a change.org petition protesting Target's move to a midnight opening, which will require employees to report to work on Thanksgiving night. The petition — dubbed "Tell Target to Save Thanksgiving" — was started Nov. 11 by Target parking lot attendant Anthony Hardwick of Omaha, Neb., and has quickly gained supporters. It has also inspired as many as 30 separate petitions on the online platform, which was recently used to protest Bank of America debit card fees.

"Thanksgiving is about being together with your family," said Bonowitz, 44. "And nobody needs to be shopping at 3 in the morning. There's just no reason for that."

He also feels it's unfair that retail workers must come to work after Thanksgiving earlier and earlier each year.

Others disagree, saying it's no longer realistic to expect the retailing world to shut down on holidays. Some say employees should realize what they're signing up for when they take the job.