Brian Pickrell, a blogger, recently posted a note on his Web site attacking state legislation that would force Wal-Mart Stores to spend more on employee health insurance. "All across the country, newspaper editorial boards — no great friends of business — are ripping the bills," he wrote.

Several sentences in Mr. Pickrell's Jan. 20 posting — and others from different days — are identical to those written by an employee at one of Wal-Mart's public relations firms and distributed by e-mail to bloggers.

Under assault as never before, Wal-Mart is increasingly looking beyond the mainstream media and working directly with bloggers, feeding them exclusive nuggets of news, suggesting topics for postings and even inviting them to visit its corporate headquarters.

But the strategy raises questions about what bloggers, who pride themselves on independence, should disclose to readers. Wal-Mart, the nation's largest private employer, has been forthright with bloggers about the origins of its communications, and the company and its public relations firm, Edelman, say they do not compensate the bloggers.

But some bloggers have posted information from Wal-Mart, at times word for word, without revealing where it came from.

Glenn Reynolds, the founder of Instapundit.com, one of the oldest blogs on the Web, said that even in the blogosphere, which is renowned for its lack of rules, a basic tenet applies: "If I reprint something, I say where it came from. A blog is about your voice, it seems to me, not somebody else's."

Companies of all stripes are using blogs to help shape public opinion.

Before General Electric announced a major investment in energy-efficient technology last year, company executives first met with major environmental bloggers to build support. Others have reached out to bloggers to promote a product or service, as Microsoft did with its Xbox game system and Cingular Wireless has done in the introduction of a new phone.

What is different about Wal-Mart's approach to blogging is that rather than promoting a product — something it does quite well, given its $300 billion in annual sales — it is trying to improve its battered image.

Wal-Mart, long criticized for low wages and its health benefits, began working with bloggers in late 2005 "as part of our overall effort to tell our story," said Mona Williams, a company spokeswoman.

"As more and more Americans go to the Internet to get information from varied, credible, trusted sources, Wal-Mart is committed to participating in that online conversation," she said.

Copies of e-mail messages that a Wal-Mart representative sent to bloggers were made available to The New York Times by Bob Beller, who runs a blog called Crazy Politico's Rantings. Mr. Beller, a regular Wal-Mart shopper who frequently defends the retailer on his blog, said the company never asked that the messages be kept private.

In the messages, Wal-Mart promotes positive news about itself, like the high number of job applications it received at a new store in Illinois, and criticizes opponents, noting for example that a rival, Target, raised "zero" money for the Salvation Army in 2005, because it banned red-kettle collectors from stores.

The author of the e-mail messages is a blogger named Marshall Manson, a senior account supervisor at Edelman who writes for conservative Web sites like Human Events Online, which advocates limited government, and Confirm Them, which has pushed for the confirmation of President Bush's judicial nominees.[Text: A PDF copy of an e-mail exchange between Mr. Manson and Rob Port, of Sayanythingblog.com.]

In interviews, bloggers said Mr. Manson contacted them after they wrote postings that either endorsed the retailer or challenged its critics.

Mr. Beller, who runs Crazy Politico's Rantings, for example, said he received an e-mail message from Mr. Manson soon after criticizing the passage of a law in Maryland that requires Wal-Mart to spend 8 percent of its payroll on health care.

Mr. Manson, identifying himself as a "blogger myself" who does "online public affairs for Wal-Mart," began with a bit of flattery: "Just wanted you to know that your post criticizing Maryland's Wal-Mart health care bill was noticed here and at the corporate headquarters in Bentonville," he wrote, referring to the city in Arkansas.

"If you're interested," he continued, "I'd like to drop you the occasional update with some newsworthy info about the company and an occasional nugget that you won't hear about in the M.S.M." — or mainstream media.

Bloggers who agreed to receive the e-mail messages said they were eager to hear Wal-Mart's side of the story, which they said they felt had been drowned out by critics, and were tantalized by the promise of exclusive news that might attract more visitors to their Web sites.

"I am always interested in tips to stories," said one recipient of Mr. Manson's e-mail messages, Bill Nienhuis, who operates a Web site called PunditGuy.com.

But some bloggers are also defensive about their contacts with Wal-Mart. When they learned that The New York Times was looking at how they were using information from the retailer, several bloggers posted items challenging The Times's article before it had appeared. One blog, Iowa Voice, run by Mr. Pickrell, pleads for advertisers to buy space on the blog in anticipation of more traffic because of the article.

The e-mail messages Mr. Manson has sent to bloggers are structured like typical blog postings, with a pungent sentence or two introducing a link to a news article or release.

John McAdams, a political science professor at Marquette University who runs the Marquette Warrior blog, recently posted three links about union activity in the same order as he received them from Mr. Manson. Mr. McAdams acknowledged that he worked from Wal-Mart's links and that he did not disclose his contact with Mr. Manson.

Wal-Mart has warned bloggers against lifting text from the e-mail it sends them. After apparently noticing the practice, Mr. Manson asked them to "resist the urge," because "I'd be sick if someone ripped you because they noticed a couple of bloggers with nearly identical posts."

But Mr. Manson has not encouraged bloggers to reveal that they communicate with Wal-Mart or to attribute information to either the retailer or Edelman, Ms. Williams of Wal-Mart said.

To be sure, some bloggers who post material from Mr. Manson's e-mail do disclose its origins, mentioning Mr. Manson and Wal-Mart by name. But others refer to Mr. Manson as "one reader," say they received a "heads up" about news from Wal-Mart or disclose nothing at all.

Mr. Pickrell, the 37-year-old who runs the Iowa Voice blog, said he began receiving updates from Wal-Mart in January. Like Mr. Beller, of Crazy Politico, Mr. Pickrell had criticized the Maryland legislature over its health care law before Wal-Mart contacted him.

Since then, he has written at least three postings that contain language identical to sentences in e-mail from Mr. Manson. In one, which Mr. Pickrell attributed to a "reader," he reported that Wal-Mart was about to announce that a store in Illinois received 25,000 applications for 325 jobs. "That's a 1.3 percent acceptance rate," the message read. "Consider this: Harvard University (undergraduate) accepts 11 percent of applicants. The Navy Seals accept 5 percent of applicants."

Asked in a telephone interview about the resemblance of his postings to Mr. Manson's, Mr. Pickrell said: "I probably cut and paste a little bit and I should not have," adding that "I try to write my posting in my own words."

In an e-mail message sent after the interview, Mr. Pickrell said he received e-mail from many groups, including those opposed to Wal-Mart, which he uses as a starting point to "do my own research on a topic."

"I draw my own conclusions when I form my opinions," he said.

Mr. Pickrell, explaining his support for Wal-Mart, said he shops there regularly and is impressed with how his mother-in-law, a Wal-Mart employee, is treated. "They go real out of their way for their people," he said.

Wal-Mart's blogging initiative is part of a ballooning public relations campaign developed in consultation with Edelman to help Wal-Mart as two groups, Wal-Mart Watch and Wake Up Wal-Mart, aggressively prod it to change. The groups operate blogs that receive posts from current and former Wal-Mart employees, elected leaders and consumers.

Edelman also helped Wal-Mart develop a political-style war room, staffed by former political operatives, which monitors and responds to the retailer's critics, and helped create Working Families for Wal-Mart, a new group that is trying to build support for the company in cities across the country.

At Edelman, Mr. Manson, who sends many of the e-mail messages to bloggers, works closely on the Wal-Mart account with Mike Krempasky, a co-founder of RedState.org, a conservative blog. Both are regular bloggers, which in Mr. Manson's case means he has written critically of individuals and groups Wal-Mart may eventually call on for support.

Before he was hired by Edelman in November, Mr. Manson wrote on the Human Events Online blog that members of the San Francisco city council were "dolts" and "twits" for rejecting a proposed World War II memorial and that every day "the United Nations slides further and further into irrelevance." After he was hired, Mr. Manson wrote that the career of Senator Lincoln Chafee of Rhode Island was marked by "pointless indecision."

Wal-Mart declined to make Mr. Manson available for comment. Ms. Williams said, "It is not Wal-Mart's role to monitor the opinions of our consultants or how they express them on their own time."

In a sign of how eager Wal-Mart is to develop ties to bloggers, the company has invited them to a media conference to be held at its headquarters in April. In e-mail messages, Wal-Mart has polled several bloggers about whether they would make the trip, which the bloggers would have to pay for themselves.

Mr. Reynolds of Instapundit.com said he recently was invited to Wal-Mart's offices but declined. "Bentonville, Arkansas," he said, "is not my idea of a fun destination."