Now she looks likely to be out of a job, thanks to her challenger's grassroots campaign. McGowan, who was active in the group Rural Australians for Refugees, recruited 500 volunteers. Younger members of her large family ran her social media campaign.
McGowan said yesterday that while she was not claiming victory, with some postal and absentee votes yet to be counted, "the level of optimism has certainly increased in [our] camp".
Mirabella, who shot to prominence as an outspoken monarchist in the run-up to the 1999 referendum on an Australian republic, is seen as part of the social-conservative right. A shadow frontbencher since 2009, she believes in tax cuts and reduced government spending.
In 2005, she accused four Liberal MPs who criticised the mandatory detention of asylum-seekers of behaving like "political terrorists".
She told veteran Liberal senator Bill Heffernan to "go and pop your Alzheimer's pills", and called Malcolm Fraser, the former Liberal Prime Minister, a "frothing-at-the-mouth leftie" for questioning the 'war on terror'.
She is loathed by the family of her former partner, Colin Howard, a law professor who died in 2011. He left her his entire estate and reportedly also gave her more than A$100,000 to help her get elected in 2001.
Now married to Colin Mirabella, a former Australian Reserve officer, she has two daughters. In 2008, when she was heavily pregnant with her first child, the then Labor MP Belinda Neal - no slouch herself in the insults stakes - told her: "Your baby will be turned into a demon by evil thoughts."