Coalition MPs breaking ranks over contentious gambling reforms is a sign of a "healthy democracy at work", the deputy opposition leader says.
Jane Hume defended internal dissent after backbenchers Pat Conaghan and Andrew Wallace crossed the floor to vote against gambling ad reforms, bucking the party line for the first time in their political careers.
Ms Hume said there had been robust debate within the coalition about the reforms and welcomed the decision of her colleagues.
"When you join the Liberal Party, you don't sign up for a frontal lobotomy the way you do in the Labor Party. We are entitled to cross the floor," Senator Hume told reporters on Wednesday.
"That's a good thing. That's a healthy democracy at work ... I think we've landed well.
"I think the balance is right."
Mr Conaghan slammed his party for being "weak" on the reforms after his time spent on the original inquiry into gambling chaired by the late Labor MP Peta Murphy, which advocated for a total ban.
Under the proposed changes, Australians would have access to a one-stop shop allowing them to opt out of online betting ads, put limits on commissions for betting agents and restrict incentives for problem gamblers.
The Nationals MP told AAP Ms Murphy would be "disgusted" by the Labor party avoiding an outright ad ban, and felt she would have thanked him for crossing the floor.
Ms Murphy's widower Rod Glover said the bill was a big improvement on the status quo in a post on social media.
But he admitted it still falls well short of the Murphy Report recommendations.
"The limits of the reforms reflect, in large part, the considerable lobbying power of the gambling industry, major sporting codes and media organisations," he said.
Debate has begun in the Senate after passing the lower house on Tuesday.
The bill before the Senate has been vastly improved, opposition communications spokeswoman Sarah Henderson said.
"No longer will wagering companies in this country, be allowed to target those who are incurring very large losses, targeting those who are addicted to gambling and making their lives hell," she said.
A partial ban on inducements has been included in the legislation, but it only applies to people during the first three months on the self-exclusion register BetStop.
The peak body for betting agencies has criticised the amendments for complicating the Australian market and playing into offshore illegal gambling sites.
Responsible Wagering Australia chief executive Kai Cantwell raised concern with the opt-out advertising register to be run by the media watchdog.
"These measures will significantly curtail our ability to advertise a legal product safely to adults,” Mr Cantwell said.
"If you push people away from the licensed, regulated market ... you don't stop them punting.
"You push them offshore, into products with no consumer protections, no support, no Betstop, and no contribution to Australian sport and racing."
Greens communications spokeswoman Sarah Hanson-Young slammed the bill, which she said was designed to fail Australian families.
"Labor has proven itself to be captured by the industry, and the Liberal Party has proven itself to be weak and toothless," she told the Senate.
Senator Hanson-Young said she has received countless first-hand accounts including of a widow receiving gambling inducements after their husband died by suicide.
"The list goes on and on and on. And yet, it doesn't seem to matter how many bodies pile up on these companies' watch," Senator Hanson-Young said.
"What a pack of bastards! How disgusting!"
Liberal senator Paul Scarr will cross the floor when the bill reaches a vote in the upper house.
"It'll be only the second time in the seven years I've served in this place that I've chosen to do so," he said.
"But I think this is such a serious issue for millions of Australians who've been impacted by gambling harm, and this is such a flawed piece of legislation that I have no choice but to do so."
