Lo Duca, 33, batted .283 with six home runs and 57 RBI over 132 games last season for Florida, his first full season with the franchise after being traded from Los Angeles in July 2004.
A two-time National League All-Star, Lo Duca is owed $12.5 million through the 2007 season. His best year came in 2001 with Los Angeles, when Lo Duca batted .320 with 25 home runs and 90 RBI in 125 games.
Published reports pin the Mets as dealing a minor leaguer for the backstop, although the New York Post noted it probably won't be top prospect Lastings Milledge.
Possibilities, as floated by the New York Daily News, could include outfielder Victor Diaz or infielder Anderson Hernandez.
The Mets – who have also tendered near-identical offers to free agent catchers Ramon Hernandez and Bengie Molina - already successfully completed one deal with the Marlins this winter, dealing three players for first baseman Carlos Delgado on Nov. 24.