Free-agent pitcher Roy Oswalt has elected to remain in the National League and is likely to sign with the St. Louis Cardinals "soon," a major league source said late Friday night. Presumably, any agreement would be pending a physical for Oswalt, who has a history of back problems. "It's not yet 100 percent," the source said. Oswalt, one of the last of the big-name free agents still on the market, had been ardently pursued by the Boston Red Sox, among others. Another team reportedly in the mix for Oswalt was the Texas Rangers, while CBSSports.com reported late Friday night that Oswalt had rejected an offer from the Detroit Tigers.