The Conservative Party is notorious for having forced some of its leaders into humiliating exits. Even a politician like Thatcher, who is still considered a hero among many conservatives in Britain, could not rely on her party in the final days of her leadership.
Since the middle of 2000, the Conservative Party has had five different leaders. Germany's equivalent — the Christian Democratic Union — has only had one leader during the same time: Angela Merkel. The Labour Party has had four leaders in the same time period, but the party has largely refrained from pushing their prime ministers or leaders out the way the Conservatives have done. Tony Blair, for instance, was allowed to serve as the Labour leader and prime minister until 2007, despite growing pressure on him to resign. Blair eventually decided to step down himself after striking a consensual deal with his successor, Gordon Brown.
In contrast, even some of the Conservative Party's steadiest leaders could not fully rely on their party's support in times of crisis.
After last June's vote to leave the European Union, David Cameron resigned as prime minister within hours despite previously pledging to remain in office no matter what the outcome of the referendum would be. But Cameron, who supported staying in the E.U., faced criticism from within his own party for initiating the vote in the first place. With his pro-E. U. supporters waning, he faced the prospect of having to deal with Conservatives whom supported Brexit, but they didn't want to keep him, either.
For every Conservative leader, there looms the fate of Thatcher, the first woman ever to be elected as the leader of a major western power and a political phenomenon who shaped Britain for decades.
In 1975, she seized the leadership of the party and led an aggressive opposition to the Labour government. The 1979 elections swept the Conservatives and her into power.
As prime minister, she initiated governmental reforms in an effort to stimulate the economy, which was mired in a recession. Her popularity peaked following the British victory in the 1982 Falklands War, winning her reelection in 1983.
But by her third term in office, her poll numbers had dropped to the point where she ultimately was forced into an internal leadership contest, being challenged by one of her former ministers, Michael Heseltine. After failing to win over the support of her party, the then-prime minister withdrew her bid to remain in power.
But even before Thatcher, there was another legendary Conservative leader to feel pressured to leave: Winston Churchill.
The Conservative Party patriarch and national hero during World War II encountered the warm embrace and the cold shoulder. After his first term from 1940 to 1945, he lost two elections but was allowed to stay on as the Conservative party leader, regardless.
Churchill triumphantly led the party back to power in 1951, but as his policies increasingly were considered failures, pressure mounted within his own cabinet for him to step down, though none dare challenge him publicly. He ultimately resigned in 1955, citing his declining health.
While Churchill was allowed to stay on as party leader in the late 1940s, despite election losses, the Conservative Party has become less lenient in recent decades. When Conservatives under John Major lost the 1997 election in the largest landslide defeat of any ruling party in almost two centuries, there were some members of parliament who urged him to stay on as the party's premier for at least a few more months. But amid intense pressure from the majority of parliamentarians, Major ended up announcing his resignation the day after the election loss.
Whereas Thatcher or Cameron had to vacate their leadership positions mainly because they remained committed to their own political goals even as other party members grew skeptical of them, former Conservative Party opposition leader Iain Duncan Smith was forced out in 2003 for the opposite reason. He had been criticized for a lack of vision and having made little impact in his two years as party leader.
If May is forced to resign in the coming days, her defeat will be due to a mixture of all the factors that led to the downfall of Duncan Smith, Thatcher, Cameron and others.
The prime minister has a vision for the country, but she has so far been unable to convince Britons that it's the right one. And at times, it felt like she was not convinced by her own agenda, as she made a U-turn on her social care plans during the campaign. She was also initially against leaving the European Union, and now appears to be one of the strongest advocates in favor of Brexit.
Described as an opportunist, she also lacks the charisma of her predecessor, Cameron, or of her foreign secretary, Boris Johnson, and insiders say that her own advisers have provoked much of the chaos that led to Thursday's election results. Her top two advisers quit on Saturday in response to the criticism.
If one of her inner-party contenders wanted to launch a leadership bid to topple her, there probably would be no shortage of arguments to defend such a move.