The source said the Marlins have been in ongoing discussions with the Royals about a possible deal for the left-handed, power-hitting first baseman. In return, Florida is seeking pitching depth, especially in the bullpen.
A couple of other teams also have expressed interest in Jacobs, including the Giants and Blue Jays. The Royals, though, may have the inside track, if the right compensation is agreed upon.
If a deal is made with Toronto, Jacobs could be used as a designated hitter. The Nationals also are in the market for a first baseman, and Jacobs could be a candidate to move there in trade talks.
In his third full season with the Marlins, Jacobs will turn 28 on Thursday. In 2008, Jacobs belted a career-high 32 home runs, while driving in 93 runs.
Eligible for salary arbitration for the first time, Jacobs projects to make roughly $3.5 million in 2009.
In his 421 career games, Jacobs has 80 home runs. He has been bothered by some nagging injuries since joining the Marlins, including a sprained ankle and broken bone in his right hand.
Jacobs played a career-high 141 games for Florida this past season, batting .247.
The Marlins are looking to get more athletic and improve defensively. Jacobs was frequently replaced at first base in the late innings for defensive purposes.
The Marlins acquired Jacobs after the 2005 season from the Mets as part of the Carlos Delgado trade.
If Jacobs is dealt, Florida's first-base options would include switching Jorge Cantu from third to first. Gaby Sanchez, who had a standout season at Double-A, is another candidate.
Joe Frisaro is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.