It has been a long time since a prince toppled a prime minister.

But this is what could happen in Australia. When the adamantly monarchist prime minister, Tony Abbott, announced that he was going to make the heavily titled, gaffe-prone Prince Philip a knight, the nation laughed — then groaned. And now, as a direct result of his action, his party will be voting this Monday to decide whether it should be allowed to vote for another leader.

It was not that Mr. Abbott’s ardent affection for the royals was a surprise. He previously served as executive director of Australians for Constitutional Monarchy and at his signing in, he swore allegiance to the queen, unlike his two predecessors, Julia Gillard and Kevin Rudd.

One of the first things he did after becoming prime minister was to try to find a copy of a portrait of a sensuous, curvy Queen Elizabeth II in a yellow evening dress, from 1954. Prints of this portrait, painted to mark a wildly successful royal tour the year after her coronation, hung in thousands of schools, scout halls and churches for decades; she was adored and held in awe. But in the 1970s these images began slowly vanishing, seen as relics of a dated, less proud Australia. After the British-born Mr. Abbott hung the portrait with pride in his office in Parliament House, one staffer grumbled to a reporter: “Next they’ll be making us curtsy when he comes into the building.”

It was not long before Mr. Abbott — astonishingly — decided to reinstate the British honors system of knights and dames. In an attempt to diminish criticism that might ensue, the first dame he appointed was the then-governor general, Quentin Bryce, who was in favor of moving from the country’s current constitutional monarchy to a republican form of government.

But this year, when he unilaterally decided to knight the queen’s husband, Prince Philip, on Australia Day, when Australians are honored for services to the community, the howls of laughter and near-universal scorn exposed the weaknesses of a leader who had failed to consult his colleagues and read the public mood. For months, he has been forced to dump, tweak or backtrack on policies in key areas like health, parental leave and education because the opposition was much stronger than he had anticipated.

Now Mr. Abbott had gone too far. Not only was the prince not Australian, but all the rousing stories of those locals who were honored that day were instantly buried under mounds of commentary attempting to fathom his decision. Even Rupert Murdoch weighed in, tweeting: “Abbott knighthood a joke and embarrassment. Time to scrap all honours everywhere, including UK.”

The prime minister dismissed the furor with a cricketing term: it was a “captain’s call,” made just because he wanted to do it. He insisted that the duke of Edinburgh had been “a great servant of Australia.”

Yet we were quickly reminded of the prince’s often insensitive and occasionally racist indiscretions: when he told the president of Nigeria, who was clad in national dress: “You look like you’re ready for bed!” and said to a female solicitor: “I thought it was against the law for a woman to solicit.” He also asked an Aboriginal leader in 2002 if “you still throw spears at each other.” Prince Philip has too often seemed a parody of a relic.

Only 14 percent of Australians agreed with the knighting, and many of Mr. Abbott’s colleagues were dismayed. Some started to speak openly about their discontent. Just a few days after Australia Day, Mr. Abbott’s Liberal National Party was soundly thrashed by the Australian Labour Party in the Queensland election.

The M.P. calling for the leadership vote, Luke Simpkins, said the knighting was the “final proof of a disconnection with the people.”

Which was odd, because when it came to the prime minister’s royal ardor, at first it looked as though the times suited him. It seemed as if the entire country was tilting back to the Windsor clan in Britain, partly because of the allure of “Will and Kate” and their chubby infant.

After all, last year, polls recorded a sharp dip in support for an Australian republic, especially among the young and the old. When Prince Harry came to visit Australia for the first time, Mr. Abbott’s face almost split from grinning when he declared, “today everyone feels like a monarchist.”

It seemed as if the country’s top lawyers agreed with him, too. In 2013, Queensland’s barristers voted to reinstate the title of queen’s counsel for the most elite of their ranks, believing it to have more cachet in the region than the title that had replaced it — senior counsel. In February last year, the state of Victoria decided that its barristers could choose that title of queen’s counsel, but that it wasn’t required.

But despite talk of a national trend, Australia is not going royal. And the prime minister’s overestimation of our attachment to the inhabitants of Windsor Castle has cost him dearly.

His future now looks perilous. Backbenchers have openly criticized him. A former Liberal premier in Victoria, Jeff Kennett, said Mr. Abbott’s leadership was “terminal,” and the influential former assistant treasurer Arthur Sinodinos said his support for the prime minister was “not unconditional.”

A chastened Tony Abbott publicly vowed to listen more, and declared that the choice of honors recipients would now rest solely with the Council for the Order of Australia.

It is unclear whether either of his most obvious rivals — Malcolm Turnbull, the communications minister, and Julie Bishop, the foreign minister — has the numbers to depose their leader (although some of his political colleagues have told me privately that Mr. Turnbull has been forcefully putting his case to them).

But perhaps the greatest twist is that both of them are republicans — Mr. Turnbull is as fervent in his desire for constitutional independence as Mr. Abbott is for the monarchy. He was chairman of the Australian Republican Movement for seven years and has continued to robustly argue his case, saying the next referendum should be held when the current queen’s reign has ended.

It would be a great irony if a leader, by trying to drag his country back to a royal past, lost a position from which he could have driven the country into the future.