British Prime Minister Theresa May delivers a speech during an election campaign visit to Langton Rugby Club in Stoke-on-Trent on June 6. (Reuters/Ben Stansall)

LONDON — The Conservative Party is notorious for forcing some of its former leaders into humiliating exits. One of those former leaders could soon be Prime Minister Theresa May. If the Conservatives push May aside, she is unlikely to be remembered as a role model by the party, as she will have been the shortest-serving prime minister in more than 100 years.

Despite her pledge to remain in office as the negotiations to leave the European Union get underway, there are indications that she will not be able to hold on to the job. One former top aide described her office as “dysfunctional” over the weekend, and a former minister acknowledged that the Tories were already plotting possible replacements via a popular messaging service. The commentary coming from the formerly loyal and hugely influential British tabloid media has also been devastating.

But who could possibly replace the current prime minister if she is ousted? Contrary to the American model, where a vice president almost immediately takes on the responsibilities of the former president, there are no regulated lines of succession for when a prime minister steps down in Britain.

Because of the specifics of British electoral rules, the leader of the party which can rely on a majority in parliament is also the prime minister. Hence, the internal leadership election of the Conservative Party would become a de facto vote over the next British leader.

The Post's Adam Taylor explains what the unexpected results from Britain's June 8 special election mean for Prime Minister Theresa May, Britain and Brexit. (Sarah Parnass/The Washington Post)

If there are more than two candidates, Conservative MPs would hold a ballot in several rounds of voting. In each round, the worst-performing candidate would be eliminated until the remaining two contenders face a runoff vote in which all roughly 150,000 members of the Conservative Party can participate.

The last leadership contest of the Conservative Party took place last year when May succeeded over contenders including Boris Johnson. The same process would have to be repeated once again — except this time, Johnson could actually win.

The outspoken former mayor of London dropped out of the race last year after leading Brexit campaigner Michael Gove suddenly decided to enter, blindsiding his former companion. Both of them being high-profile Brexiteers, Johnson quit the contest, saying he feared that those in favor of leaving the European Union would have had to decide between him and Gove, and potentially empower a contender not in favor of Brexit as a result.

[Theresa May’s disastrous gamble on the future of Britain]

Boris Johnson dangles from a zipwire in London's Victoria Park on Aug. 1, 2012. (Rebecca Denton/Getty Images)

Johnson is now the foreign secretary and has frequently been mocked for his unusual — and sometimes embarrassing — handling of diplomatic challenges. He has been mocked as a “nasty young kid” by a former director general of the World Trade Organization, and during one of his most legendary photo calls he became stuck hanging on a zip wire.

A recent poll suggested that many Britons do not believe Johnson would be qualified for the office of prime minister, but some Tory members say that he would at least be less out of touch with voters than May.

Another competitor could be the current home secretary, Amber Rudd — who holds the same position May had before becoming prime minister. Being home secretary is considered one of the most challenging jobs within the British government, but some doubt whether she has the profile to become prime minister. In her own constituency, Hastings & Rye, Rudd only held on to her seat in Thursday's election by the narrowest of margins — 346 votes.

Chancellor Philip Hammond could also attempt to win the internal contest. He clashed with May, following Thursday's election, saying that she should appoint a deputy prime minister and sack her two top advisers. On Saturday, those two did resign, in a possible indication of Hammond's rising influence. Hammond would have the experience and profile needed to secure a Brexit deal in the negotiations, which will likely be used to determine whether the prime minister who will lead Britain out of the E.U. failed or succeeded.

David Davis, the secretary of state for exiting the European Union, could also have a chance to become the party leader, mainly due to the focus of his ministry. Analysts also believe that the leader of the Scottish Conservative and Unionist Party, Ruth Davidson, might be a possible replacement for May. While the Conservative Party suffered losses in much of Britain, its Scottish branch, led by Davidson, had its best result in more than three decades on Thursday.

At least publicly, several of May's possibly replacements continue to back the prime minister. Davis said on Monday that he was not interested in replacing her, following similar remarks by Johnson. Hammond, however, has indicated that he would only continue to support May if she moderated her stance on Brexit.

Apart from some of those more well-known names that are circulating, the Conservative Party might also opt for a lesser-known candidate who would be able to start from scratch without being restricted by previous inner-party disputes. After all, one year ago, one name was missing from many lists of the most likely prime ministerial candidates: Theresa May.

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