The younger McGwire submitted a 58-page proposal to a number of publishers last week, offering to tell the story of how he had introduced his brother, who is eighth on the career list for home runs, to performance-enhancing drugs.

But several publishers who have seen the proposal for the book, which Jay McGwire is calling “The McGwire Family Secret: The Truth About Steroids, a Slugger and Ultimate Redemption,” have passed on it.

“There are so many things about it that I find suspect,” said David Hirshey, the executive editor of HarperCollins. “If Jay McGwire is to be believed, he says he is setting the record straight out of quote love unquote for his brother, although a cynic might say it’s out of love for a big payday.”

Hirshey said that McGwire’s proposal landed on his desk the week that a grand jury met to hear evidence that could lead to the indictment of Roger Clemens for perjury after he testified in a Congressional hearing that he never used performance-enhancing drugs.

McGwire’s proposal also arrived as “Based Loaded,” a memoir by Kirk Radomski, a confessed steroids dealer, is poised to hit bookstores Tuesday.

Frank Scatoni, McGwire’s agent, did not respond to an e-mail message or call seeking comment.

In his proposal, first reported by the Web site deadspin.com, Jay McGwire, a bodybuilder, said he introduced his brother to steroids in 1994. That contradicts claims made by José Canseco in his 2005 memoir, “Juiced: Wild Times, Rampant ’Roids, Smash Hits and How Baseball Got Big,” in which he said he started injecting Mark McGwire with performance-enhancing drugs in 1988.

William Shinker, the president and publisher of Gotham Books, a division of Penguin Group USA that published “Game of Shadows,” a book about steroids in sports by the journalists Mark Fainaru-Wada and Lance Williams, said he also passed on McGwire’s book. He said he was in part turned off by the fact that the book would be “a brother ratting out a brother.”

Shinker said he also believed that audiences might be fatigued with Mark McGwire’s story after his Congressional testimony four years ago, in which he declined to answer questions about whether he had used steroids.

There is evidence that a broader sense of steroid weariness is setting in among book-buyers, after some early successes. “Juiced,” published by Regan Books, a now-defunct imprint of HarperCollins, sold 157,000 copies in hardcover, according to Nielsen BookScan, which tracks about 70 percent of sales. “Game of Shadows,” published in 2006, sold 124,000 copies in hardcover. But “Vindicated: Big Names, Big Liars, and the Battle to Save Baseball,” Canseco’s follow-up to “Juiced,” published last year by Simon Spotlight, sold only 22,000 copies in hardcover.

“The whole steroid thing has been done,” said Frank Sanchez, the head buyer at Kepler’s Books and Magazines, an independent bookstore in Menlo Park, Calif. “There have been so many articles in local papers and magazines, so people feel like they’ve already read about that and they just don’t care anymore.”

At Borders Group, Zan Farr, a sports book buyer, said she had ordered Radomski’s book in just enough quantities to stack on tables at the front of the chain’s stores.

“I’m not sure people in this environment are going to be coming to it the same way they did the other books,” Farr said.