These two have been linked in speculation for about a week, and the interest has carried over to the Winter Meetings, the source said. Sanchez is a 26-year-old left-hander with tremendous upside.
In addressing the Florida beat reporters on Monday night, Marlins president of baseball operations Larry Beinfest said: "I'm not confirming or denying rumors."
It's clear the Marlins are at the Meetings to explore options to improving in the areas of pitching and defense.
Along with Cantu, right fielder Jeremy Hermida also has been the subject of trade talks. Some reports have the left-handed-hitting outfielder linked to the Cubs, Rays and Braves. One scenario has Hermida possibly being moved to the Rays for shortstop Jason Bartlett. That appears unlikely, an American League source noted.
Beinfest said the Marlins plan on keeping All-Star Hanley Ramirez at shortstop, which makes bringing in Bartlett appear unlikely. Florida seems ready to retain Ramirez and second baseman Dan Uggla as the middle infielders.
"We're different from most teams, given the offense we get up the middle," Beinfest said. "We believe [Ramirez] can play short. He's an All-Star-caliber player at short."
Ramirez and Uggla combined for 65 home runs in '08.
Beinfest added Ramirez is athletic enough to play the outfield, but that isn't something being considered.
"Could he play the outfield? I think he can do anything on the baseball field," Beinfest said. "Could he play the outfield? Yes. But he can also play shortstop, and that's where he will be."
Cantu has clearly developed a market after his strong first season in Florida. The 26-year-old belted 29 home runs and his 95 RBIs paced the team. Arbitration-eligible, the third baseman's salary projects to rise to between $3.5 million to $4 million.
Cantu was the Marlins' regular third baseman, but in late innings, he frequently was used at first base. He appeared in 129 games at third base and 66 at first base.
Already this offseason, Florida has dealt first baseman Mike Jacobs to the Royals for reliever Leo Nunez. If Cantu remains with the Marlins, he is an option to switch to first base.
If the Marlins do deal Cantu, prospect Gaby Sanchez would have the inside edge to win the first-base job. Options for third base would be Emilio Bonifacio, Dallas McPherson and Wes Helms. Helms, though, is regarded as a backup at third base and first base.
Sanchez posted a 9-12 record with a 5.01 ERA in 29 starts. In 158 innings, he struck out 157.