Cory Bernardi is no stranger to letting rip with his opinions and putting the noses of his political friends and foes out of joint.
The conservative Liberal senator now appears set to quit the coalition as early as Tuesday to establish his own political party.
So, exactly who is this South Australian politician sending shock waves through the Turnbull government?
Bernardi was first elected to the Senate in 2006 after serving as president of the SA Liberals and vice president of the federal party.
He has long attracted attention for his outspoken views on same-sex marriage, Islam, climate change and race-hate laws.
Before entering parliament, he rowed for Australia before a back injury cut short his sporting career.
Bernardi then took over the family pub before a year spent in isolation with tuberculosis spurred him to pursue politics.
A social conservative and economic liberal, he believes in small government, low taxes and free enterprise.
Bernardi has bemoaned the coalition neglecting its base by drifting from those values and haemorrhaging votes to fringe parties including One Nation.
He was a key figure in the ousting of Malcolm Turnbull for Tony Abbott in 2009 over an emissions trading scheme.
Bernardi has twice been demoted from the frontbench for making controversial comments, including linking same-sex marriage to bestiality.
He established the Conservative Leadership Foundation in 2009 and last year formed the Australian Conservatives movement, which is said to have around 50,000 members.
He spent several months during 2016 seconded to the United Nations in New York as a parliamentary observer.
Bernardi was enraptured with the rise of US President Donald Trump, snapping pictures with some of his top aides and posting a self portrait to social media wearing a "Make Australia Great Again" cap.
Bernardi last week warned this would be a testing year for both the government and opposition.
"Unfortunately there are too few in our body politic willing to take the path less travelled - a trustworthy track that has fallen out of use," he said.
"For the sake of our nation, we must get back on track."
