Federal Cabinet has signed off on plans to hold the same-sex marriage plebiscite on February 11 next year, and to allocate public funding for both the "yes" and "no" campaigns.

Key points: Proposal to be put to Coalition MPs at party room meeting

Proposal to be put to Coalition MPs at party room meeting ABC understands Cabinet agrees to allocate $7.5m to each campaign

ABC understands Cabinet agrees to allocate $7.5m to each campaign Cabinet wants to cap tax deductible donations to each campaign at $1,500

The proposal will be put to Coalition MPs at their party room meeting in Canberra today and will increase pressure on Labor to declare its hand and state whether it will support the legislation needed to hold the plebiscite.

Ministers have also agreed that the question to be put to voters will be: "Should the law be changed to allow same-sex couples to marry?"

But in a move that will inflame tensions within the Coalition, the ABC understands Cabinet has agreed to allocate $7.5 million in public funding to each campaign.

Liberal-National MP — and gay marriage advocate — Warren Entsch has warned the plebiscite "won't get up" if taxpayers' money is used to fund the "for" and "against" cases.

But conservatives Andrew Hastie and Cory Bernardi have joined calls from Eric Abetz and Kevin Andrews for public funding to be made available.

Mr Hastie told the ABC if the Government was going to put a vote to the Australian people, it needed to make sure they were informed of both sides of the argument.

'No' campaign could drive people to suicide: Shorten

Prime Minister Malcolm Turnbull hinted yesterday the two campaigns would receive public funds but tried to sooth tensions by guaranteeing the plebiscite would be "utterly fair".

"Any funding provided to the 'yes' or 'no' case will be scrupulously equal and fair as it always has been," he told Parliament yesterday.

As well as the public funding, the ABC understands Cabinet wants to cap tax deductible donations to each campaign at $1,500 per individual.

The fate of the plebiscite ultimately rests in Labor's hands, and yesterday Opposition Leader Bill Shorten appeared to strengthen his argument against the vote.

Introducing a private members bill into Parliament to legalise same-sex marriage, Mr Shorten warned the "no" campaign could drive young people to suicide.

"A 'no' campaign would be an emotional torment for gay teenagers and if one child commits suicide over the plebiscite, then that is one too many," he told Parliament.

Gay brother questions Q&A panellist over plebiscite

During last night's episode of Q&A, the brother of National Party senator for Victoria Bridget McKenzie questioned his sister about the plebiscite.

"Given the majority of parliamentarians and Australians now support marriage equality, is a $160-million plebiscite necessary and what impact do you think the debate will have on the emotional wellbeing of gay and lesbians like me?" Alastair McKenzie asked.

Sorry, this video has expired Senator's gay brother questions her about same-sex marriage plebiscite on Q&A

Ms McKenzie responded by saying it would only be damaging if Australians chose not to respect each other's views.

She added that she believed same-sex marriage was a "conscience issue".

"I believe it is a conscience issue and it is that the definition of marriage is between a man and a woman," she said.

"Polls would suggest I'm in the minority."