NEW YORK (AP) -- A new book about Sen. Barack Obama has intensified a rivalry between two powerful competitors: Barnes & Noble, Inc. and Amazon.com.

Chelsea Green Publishing, a small, liberal publisher based in Vermont, is releasing Robert Kuttner's "Obama's Challenge," a call for Obama to enact a bold, progressive economic agenda. It plans to distribute copies at next week's Democratic National Convention, where Obama is expected to get the party's presidential nomination.

Angering both Barnes & Noble and independent sellers, the publisher also will distribute coupons that can be redeemed exclusively through Amazon.com's BookSurge, a "print-on-demand" service that through digital technology enables books to be printed in small quantities.

According to Chelsea Green, several independent stores complained, withdrew their orders and even threatened to boycott other Chelsea Green books. In an open letter to booksellers, Chelsea Green president Margo Baldwin defended her decision.

"This is about a publisher's commitment to its author to get one of a very few pro-Obama books out into the marketplace in the shortest amount of time," she said, noting that its 75,000 first printing was a record for Chelsea Green.

But the biggest response came from Barnes & Noble, which had ordered several thousand copies. It told Chelsea Green it would not stock "Obama's Challenge," but only make it available through special orders or its Web site, http://www.bn.com .

Chelsea Green restricted the book's availability by giving one company a two-week exclusive, Barnes & Noble spokeswoman Mary Ellen Keating said Monday.

"Our initial order was based on the book being available to all booksellers simultaneously - an even playing field," she said.

Baldwin said of Barnes & Noble, "They are not going to bully us and the book will be a huge success in spite of their boycott."

Barnes & Noble's action comes at a time when the superstore chain, and all booksellers, face increasing competition from Amazon.com, which has grown its market share steadily in recent years as book sales overall were flat. The online seller told The Associated Press recently that it was talking to publishers about having books sold exclusively through its Kindle e-book reader.

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