The Texas Rangers remained optimistic Sunday that pitcher Josh Beckett would anchor their starting rotation next season. But a baseball source with knowledge of the negotiations said the Marlins won't trade their 2003 World Series hero without receiving a top pitching prospect from Texas. The source also said there is a chance Beckett would remain with Florida in 2006 because the Marlins won't make any concessions in negotiations for their right-handed pitcher. At least six teams are interested in Beckett, but the Rangers are one of four teams in serious pursuit of him, the source said, adding that there is another team that has presented Florida with a more attractive proposal than the one presented by Texas. The source would not identify that team, only to characterize the Rangers as being second in the pack. One of the teams pursuing Beckett is the Boston Red Sox. The Detroit Tigers are thought to be another team in the Beckett hunt. As of Sunday night, the Rangers felt they had "given it their best shot," according to an industry source, and were waiting to hear back from Florida. On the table is a deal to send Beckett and third baseman Mike Lowell to the Rangers for third baseman Hank Blalock. The original deal called for Texas to include either left-hander John Danks, the organization's first-round draft pick in 2003, or right-hander Thomas Diamond, the team's first-round pick in 2004.