Finch will consider his T20 future after the upcoming World Cup but should CA decide they want one captain across both codes he may have to hand over the role.
Asked on Tuesday morning whether he would put up his hand for the one-day captaincy, Marsh said the role was not for him.
"Probably not to be honest, I'm out of the race," he said. "I've had to get the body right for this World Cup. The World Cup is such an exciting prospect for all of us, to worry about that sort of stuff [captaincy] is just not on my radar at the moment.
"Cricket Australia has a decision to make after the World Cup...it's really not something I've thought about."
While stopping short of a firm endorsement of Warner, Marsh acknowledged the 35-year-old could bring a lot to the job.
"He's a great leader among our group," Marsh said. "As far as all the decisions go, I certainly steer clear of all those conversations. But he's a great man to have in the squad."
Marsh crunched 36 in his now-usual No.3 role in the T20 series opener against England in Perth on Sunday. The teams will go head-to-head again on Wednesday at Canberra's Manuka Oval.
Allrounder Marsh did not bowl in Perth, but said it remained the plan for the World Cup.
"The body's feeling good at this stage," he said. "Hopefully I'll be right to bowl in the first warm-up game but with Stoin [Marcus Stoinis] back bowling now, it's a bit of a luxury we can work as a team and really build towards the World Cup.
"We're going to get four overs out of us; some days it's me, some days Stoin, and some days Maxi [Glenn Maxwell]. The best T20 teams in the world over the last five, six years, have that flexibility...we're almost a team within a team."