Pauline Hanson has launched a personal attack on Jacqui Lambie as debate about drug testing welfare recipients takes a nasty turn.
The One Nation leader demanded a "please explain" from Senator Lambie after dragging her family into the fray.
"Her child has been on drugs and you wouldn't knock back something that could possibly help people like her son," Senator Hanson said in Canberra on Tuesday.
"That's why I'm supporting this. Why is she knocking this back? Who's got in her ear?"
Senator Lambie is refusing to support the drug-testing trials until more rehabilitation beds are available.
The Tasmanian crossbencher was quick to respond after her son – who suffered with ice addiction – was roped into the debate.
"My son is an example of what happens when you have access to the support and rehab services you need," she tweeted.
"Five hundred thousand Aussies don't have access to those services. My son has moved on from the past."
The Morrison government wants to screen 5000 Newstart and Youth Allowance recipients for illicit substances.
About 500 people are expected to fail one test.
"Not one cent of their welfare payments will be reduced," Social Services Minister Anne Ruston said.
"What we will seek to do is to put them onto a card, an income management card, that will require 80 per cent of their income to be quarantined and not accessible in cash."
Only 150 people are expected to test positive a second time.
These 150 welfare recipients could each be eligible for up to $65,000 worth of treatment and support.
"If they fail a second time then we'll seek to support them into a rehabilitation program to deal with their drug dependency issue," Senator Ruston said.
The government has promised to spend $10 million boosting rehabilitation services across the three trial sites.
Prime Minister Scott Morrison is puzzled by the level of opposition to his plan.
"You try things because these are difficult problems and you have to ensure that you're having a go at trying to fix these problems," he told reporters at Parliament House.
"Now, if you're not prepared to do that, well, you're clearly not committed to trying to address this issue."
Shadow treasurer Jim Chalmers said resurrecting the twice-rejected idea was a cynical attempt to whip up political conflict.
"The prime minister now wants you to pee in a cup in a demeaning way as a part of his picking fights with the Labor Party," he said.
Opposition Leader Anthony Albanese also said the plan to drug test people on welfare was a political tactic, not a legitimate policy.
"The prime minister needs to stop looking for distractions from the main game," Mr Albanese said.
"The main game in this country is the economy and the fact that people are really struggling, and the prime minister is out of touch."
The coalition will re-introduce legislation underpinning the drug-testing trials to the lower house later this week.
Do you have a story tip? Email: email@example.com.