Opposition leader Tony Abbott has moved a censure motion against the Prime Minister in parliament as the Coalition stepped up its campaign for the NBN Co business plan to be made public.
A censure motion is used to express disapproval of a particular minister, his or her policy, or of the government.

Although the motion received 74 votes in favour and 71 against, it was ruled short of an absolute majority by speaker Harry Jenkins and therefore defeated.
It capped a fiery delay in politics that saw a Liberal motion to stall debate on the NBN in the Senate and Opposition communications spokesman Malcolm Turnbull's private members bill seeking a cost-benefit analysis defeated in the Lower House - both by tight margins.
Abbott continued the Coalition's attack by bringing the censure motion against Julia Gillard, which was seconded by Turnbull.
He demanded that Gillard "immediately publish the NBN business case."
"We've heard the Prime Minister assert repeatedly that the NBN is in the national interest," Abbott said.
"We require the PM to stop asserting it and start proving it. If it's as vital and necessary as she says, why is she so scared to release the business case she has had for some time?"
"We are capable of reading that document. We want to read that document.
"This is a Government that wants evidence-based policy but who won't release the evidence on which it's policy is based.
"Shame, shame on this weak and cowardly Government that won't give the Australian people the evidence."
Abbott echoed Coalition arguments in the Senate that the Government reveal the NBN Co business plan to ensure parliamentarians had all the analysis available to them before they voted on proposed legislation including the Telstra split bill.
"Let's make a decision on the best evidence available," Abbott said.
"Give us the evidence. Don't expect us to make a decision without the evidence.
"Let the sunlight in. And give us the evidence. Let the sun shine in on the business case for the NBN. The Government doesn't have the courage to produce the evidence for this."
Gillard responded that the Coalition was not interested in the details of the NBN Co business plan, only in pulling out details it could use to try and shoot the project down. She said the opposition was playing politics.