Washington's XM Satellite Radio Holdings Inc. plans to announce a deal worth as much as $650 million with Major League Baseball today that will enable the company to carry most regular and postseason games over the next several years beginning with Opening Day 2005, said a source familiar with the deal.

For the young-but-growing satellite radio industry, baseball's deal with XM is another marker of credibility and viability. Earlier this month, New York rival Sirius Satellite Radio Inc. (launched in 2002) inked a five-year, $500 million deal to bring Howard Stern on board after his contract with Infinity Broadcasting Corp. expires in January 2006. Last year, Sirius paid more than $220 million for the rights to broadcast all NFL games, adding to NBA and NHL packages.

XM, which began service in 2001, beams more than 100 music, talk and sports channels to 2.5 million subscribers for $9.95 per month. It lacked a major professional sports plan, though it airs some baseball games through its ESPN channels and recently launched channels with major-conference college football games.

For baseball, XM plans to devote up to 16 channels to America's pastime beginning next season. Up to 15 of the channels will carry nearly every daily game between the 30 big-league teams (if fewer teams play on a given day, fewer channels will be required) while the final channel would be devoted to other baseball programming, such as broadcasts in Spanish and the replay of archived games.

The games will appear on XM's standard service at no extra cost, said the source, who spoke on the condition of anonymity because the deal had yet to be publicly announced.

Under the terms of the deal, XM will pay baseball $59 million per year for the first eight years, and the league has three one-year options to renew at $60 million per year thereafter, the source said.

There are more than 2,400 games during each 162-game season and XM's deal includes more than 2,000 of them. The deal also includes some spring training games.

XM will be allowed to broadcast local games that will also be heard on traditional radio networks. Washington-area XM subscribers, for instance, will be able to hear games played by the Baltimore Orioles and the soon-to-be-relocated Montreal Expos.

The announcement is scheduled to come today at a joint news conference with baseball commissioner Bud Selig and Hugh Panero, chief executive of XM.

XM plans to carry nearly every game starting next season, setting aside up to 16 channels to do so.