Bill Shorten's support for boat turnbacks will help the Greens win votes in Victoria but should not cost Labor any lower house seats at the next election, experts and strategists say.

But the policy will kill off any hope of a Labor resurrection in the seat of Melbourne, held by the Greens' Adam Bandt since 2010.

Labor's policy on boat turnbacks and asylum seekers may cost it votes to the Greens.

Monash University political expert Paul Strangio said the policy was a clear sign of Labor's focus on seats in NSW and Queensland at the next election.

"Every time Labor has endeavoured to narrow the policy gap with the Coalition on asylum seekers there is little evidence it has done them any favours politically," Dr Strangio said.