Pauline Hanson has warned legalising same-sex marriage could result in a ban on children calling their parents 'mum and dad'.
The One Nation leader has told parliament she will ignore a majority "yes" result of a postal survey on the issue.
"I feel it's a sham, it's farcical and it's a waste of money," she said of the $122 million ballot.
Senator Hanson also slammed gay couples for trying to "take the word 'marriage'".
"Why won't you try and compromise?" she said.
Senator Hanson warned marriage equality meant schoolchildren would be banned from calling their parents "mum and dad" so as not to offend the children of same-sex couples.
Meanwhile, she said proposed anti-vilification laws being debated in the Senate on Wednesday would shut down the "no" campaign and free speech.
Earlier senior Labor figure Penny Wong delivered an impassioned speech urging the prime minister to protect children like her own.
"How do you think it feels for children in same-sex families ... to be told politely and courteously `Actually you're not quite normal, your families aren't as good'?" asked Senator Wong, who is a parent in a same-sex relationship.
The bill makes it an offence to vilify, intimidate or threaten to cause harm to a person on the basis of their sexual orientation, gender identity, intersex status or religious conviction during the survey.
Senator Wong lamented that those opposed to gay marriage were using "odd, bizarre and unconnected things" to make their argument.
"They want to talk about our children, they want to talk about - what's the phrase - `radical gay sex education'."
The bill could not protect the LGBTI community from hurt.
Greens senator Janet Rice, who married her transgender wife Penny 30 years ago when her partner was Peter, said she wanted to be able to hold her partner's hand in public, the way they used to, without fear of abuse.
"We used to hold hands, we used to kiss in public but over the last 13 years we self-censor," she told parliament.
"We generally don't hold hands in public, we get used to the fact that if we are holding hands in the street we need to be ready for the possibility of having a car driving past, wind down its window and hurl abuse at us."
Cabinet minister Mathias Cormann said the bill was seeking to add extra protections to existing safeguards in federal, state and territory legislation.
"This will help ensure the integrity in this process and that Australians can have complete confidence that the outcome of the survey reflects the freely given views of the respondents," he said.
Conservative crossbencher Cory Bernardi also opposes the legislation, warning there would be spurious claims from people claiming to be upset.
"This is essentially 18C on steroids to protect people from being upset," he said, referring to race hate-speech laws he has fought to scrap.
It was "wholly inappropriate" that Attorney-General George Brandis has responsibility for judging complaints, given he supports marriage equality.
"Do we want really a cheerleader... anyone who is a partisan cheerleader for a side in a camp to be rendering any form of judgment about the conduct of one side or the other?" he said.