Liberal leadership speculation has reached fever pitch, with Foreign Minister Julie Bishop forced to tell Sky News on Tuesday she wasn’t sharpening her knives: “I am not campaigning for the job of prime minister, I am not ringing the backbench asking for support … I will not challenge.”

But that doesn’t mean Abbott should rest easy. Pollies have a habit of professing their undying support for their leaders — right before they stab them in the back.

In May 2010, then-deputy prime minister Julia Gillard ruled out any possibility of replacing Kevin Rudd as leader before the election

When journalists asked her about the likelihood of her challenging then-prime minister Rudd for the top job, she told them they would be better off asking if she were anticipating a trip to Mars.

”I think [the leadership speculation is] ridiculously funny and a grand distraction. I’m Deputy Prime Minister of this country. It’s what I chose.

“There’s more chance of me becoming the full-forward for the Dogs [Western Bulldogs AFL team] than there is any chance of a change in the Labor Party.”

A month later Gillard requested Rudd hold a ballot for the leadership of the Labor Party — shortly after she was informed that she had the numbers.

But she didn’t need the numbers in the end, as Rudd declined to contest, and instead resigned — beginning a four-year political rivalry that illustrates the contradiction by politicians involved in these spills.

Following Rudd’s failed attempt to regain Labor leadership in a second spill in 2012, he promised Gillard that he would not challenge again, and would be by her side for the next federal election.

“I dedicate myself to working fully for her re-election as the prime minister of Australia — and I will do so with my absolute ability dedicated to the task.”

Just over a year later, Simon Crean called on Gillard to hold a snap ballot amid persistent leadership tensions. Many Labor MPs were expecting Rudd to contest the ballot, but he stood by his pledge. The former PM later announced there were “no circumstances” in which he “would ever contest the position again”.

“There’s no way I would ever be party to a stealth attack on a sitting prime minister.”

Kevin Rudd was sworn in as prime minister for a second term only three months later.

The Rudd-Gillard-Rudd years were not the first, or even most notable, Labor turmoil. After Paul Keating tried and failed to roll then-prime minister Bob Hawke, he swore off any future attempts: “I had one shot in the locker, and I fired it,” Keating said, saying he was strongly considering retiring from politics.

That mentality lasted for only six months, and with many in the Labor caucus quickly losing confidence, Keating went back on his word and challenged again in December of that year. He won and became prime minister.