"A rental, it may help you in the short term," president of baseball operations Michael Hill said. "We want something we can move forward with. I think that will definitely influence the direction we go."
The Marlins will have to make a decision on a fifth starter by the fifth game after the All-Star break, which would be July 22 at home against the Braves.
An internal option is long reliever Jacob Turner returning to the rotation. But the team could pull off a trade before that point.
"We're obviously looking to see if there is opportunity for us to upgrade our rotation," Hill said. "But if we aren't able to upgrade our rotation, that's an option [Turner] we will look at internally."
Miami also is seeking a second baseman with speed.
The Marlins, despite losing road series on this trip at Arizona and New York, still believe they can make a playoff push.
"Hopefully we start playing better and we start winning games and we put ourselves back in this race," Hill said. "I don't think we're out of it by any stretch of the imagination. I think you've seen clubs that may look down, get hot, and thrust themselves right back into this thing.
"We still have a number of games against the teams that we're chasing in Atlanta and Washington. We still believe in that clubhouse. We just need to execute better, play better and win more games."
Pretty much all the core players on the roster are under club control through at least 2015. Casey McGehee, for instance, was a free-agent pickup this year, but the 31-year-old will still be eligible for arbitration in 2015.
The Marlins are looking to keep adding onto its roster, not subtract.
"We're never short-sided with anything that we do," Hill said. "There is always an eye on the present. We never lose sight of the future and what we're trying to build. We want to build sustained winning here. We do control all of our roster, for the most part."