Tasmania's Labor has stepped up pressure on the Federal Government to change its mind on the NBN rollout in Tasmania.

It is offering to give NBN Co free access to the state's power poles in a bid to have optic fibre rolled out across the state.

Under the policy, Premier Lara Giddings says the state would forgo $25 million over 20 years in rental fees to its poles and wires business, Aurora Energy.

Ms Giddings says NBN Co should switch the underground rollout of the fibre optic cable to an overhead rollout, which would be cheaper and faster to install.

"When we're offering to NBN to use our poles for free, we can guarantee you that it will cost you far less," the Premier said.

"At the moment it costs about $400 a metre to put optic fibre in the ground in comparison to $65 a metre to use our power poles."

NBN Co revealed last week that is some cases, fast broadband would be delivered via the existing copper network, not fibre.

The decision angered the IT sector and local businesses.

The Premier says she told the head of the NBN Co, Ziggy Switkowski, about the offer in a meeting last week and she hopes her election pledge should help reverse the wind-back.

"It shows that the state can be involved in this project, the state does have a role in this project," she said.

"We are offering free access to our poles to help drive down the cost to NBN Co to deliver the promise that Tony Abbott made before the last election, now backflipped on."

Turnbull unimpressed with offer

The offer has been rubbished by the Federal Communications Minister.

Malcolm Turnbull says the rental of the poles is only a very small part of the overall cost to complete an aerial rollout.

He says the largest cost to NBN Co is what Aurora Energy charges for the work it carries out to get the poles ready.

"The offer that Lara Giddings has made is certainly worth the NBN Co looking at, but...it is a very small part of the overall cost," he said.

"The rental that Aurora has been charging NBN Co is a little bit less than $40 per pole it is a very small part indeed of the overall cost of using Aurora's poles.

"So she's not really offering very much, in other words."

State campaign pressure

During last year's federal election campaign, the Coalition pledged to honour the Tasmanian contracts for the rollout.

The Liberal Party is ahead in the polls for next month's state election, but leader Will Hodgman has admitted the change to the copper network plan could cost the Liberals next month's state election.

Opposition energy spokesman Matthew Groom avoided answering a question as to whether he feels the same way.

"The commitment we make to the Tasmanian people is to do all we can to continue our constructive dialogue with Malcolm Turnbull and the Commonwealth Government to deliver the best possible outcome," he said.

"That's our commitment and I will say, having spoken directly to Malcolm Turnbull in relation to the NBN, that in Malcolm Turnbull Tasmania has a friend."

Mr Turnbull would not respond to the suggestion, but insists he has not broken any promises to Tasmanians about the rollout.

"Will can run his own commentary on that the position that I've stated is the one I've stated before the election, and it's the one I've stated since the election, so nothing has changed."

Federal Denison Independent Andrew Wilkie agrees the Federal Government's NBN policy could swing the election result.

"It may well cost him the election, because as I go about my business, and I meet a lot of people, the NBN is a number one issue for many constituents," he said.

He is accusing the Federal Liberal Party of misleading Tasmanians about broadband policy.

Greens outline state-based plan

The Tasmanian Greens want to set up a state-owned company to complete the rollout.

Leader Nick McKim says Tasmania could deliver the project more efficiently and more cheaply than the Federal Government.

He says details and costings still need to be worked out, but he believes the Greens could attract private investment.

"Of course there's a lot of work that would need to be done before we fully understand the scale and the cost of this proposal, but we believe it can be done," he said.

"It can be done by partnerships with the private sector including some of the super fund and private capital investors."

Mr McKim has admitted the party has only come up with the idea in the last five days, following the NBN Co's backflip on the fibre rollout.

Last year, the Premier asked Aurora to investigate the use of the power pole network for the NBN rollout.