Britain could get its third prime minister in just two-and-a-half years if current leader Theresa May loses a vote of no-confidence within her Conservative Party.
The vote was triggered on Wednesday morning and the result is expected to be released at 2200 CET.
May, who vowed to fight to keep her job during a speech earlier, is heavily tipped to survive the vote but several figures have emerged as potential contenders should Conservative MPs disavow her.
Here are those who could throw their hat in for the most powerful job in Britain.
A former London mayor and ex-Foreign Minister in May's government, Johnson is one of the Prime Minister's most vocal critics.
He resigned his Cabinet position in July in protest over May's Brexit plan, which he denounced as too soft and has since then eviscerated her exit strategy in regular columns for the Daily Telegraph newspaper.
The 54-year old is a controversial figure having been accused of misleading the public during the EU referendum campaign in which he was one of the Leave camp's leading figures.
Still, he remains very popular with the party's membership: people queued for hours to see his speech at the Conservative Party Conference in October, which was widely seen as a pitch to replace May.
He called for the party to return to its roots with tax cuts and strong policing and urged May — against whom he ran for the leadership of the Conservative Party in the 2016 contest — to back a hard Brexit.
As his party descended into chaos on Wednesday, Johnson, usually verbose, remained mute on his voting intention.
According to Oddschecker, Johnson is the current favourite to take over as Tory leader.
Raab, 44, quit his job as Brexit minister last month after May announced that she had reached a withdrawal agreement with the EU. He had been in the job for only five months.
He then indicated that he would oppose the deal in the scheduled December 11 vote in parliament before it was postponed by May.
Unhappy with the backstop arrangement to avoid a hard border in Ireland, he urged May to return to Brussels "with a revised offer, which remedies the flaws" and should that fail to step up preparations for a no-deal Brexit.
He was elected as an MP in 2010 and campaigned for the UK to leave the EU.
Like Johnson, he has remained tight-lipped over how he plans to vote in Wednesday's confidence ballot.
An admirer of former Prime Minister Margaret Thatcher, Javid, 48, is a well-liked figure in the Conservative Party.
He was elected as an MP in 2010, leaving behind a successful career in banking, and started occupying government positions in 2012.
Javid became the first ethnic minority Home Secretary — his Pakistani parents immigrated to the UK in the 1960s — in April after Amber Rudd resigned.
He campaigned for the UK to remain in the EU but has since then revealed a more eurosceptic stance.
He announced ahead of the confidence vote that he was "backing the Prime Minister 100%."
Hunt, 52, picked up the Foreign Minister mantle in July following the resignation of Boris Johnson.
Prior to that he was the country's longest-serving Health Secretary, a position he held for six years and which made him unpopular with medical staff staging their first all-out strike in the National Health Services' history.
He campaigned for the Remain camp ahead of the EU referendum but has since said that he changed his mind because of the bloc's "arrogance" in the negotiations.
He said he was backing May tonight and described her as "the best person to make sure we actually leave the EU on March 29".
Gove, 51, pulled off an unexpected career comeback after the 2016 leadership contest in which he was widely seen as having betrayed his fellow high-profile Leave campaigner Boris Johnson by putting his name in the running.
But defeated by May, he retreated to the backbench before returning to government again in June 2017 as environment minister, a role he dedicated himself to energetically.
He's offered the prime minister his support ahead of the vote and urged "every Conservative MP to do the same."
A close ally of May, Amber Rudd returned to government last month as Pensions Secretary following Esther McVey's resignation over the Brexit deal.
Rudd, 55, had left her Home Secretary position just six months earlier because of the government's handling of the Windrush scandal.
A prominent Remain campaigner during the EU referendum campaign, Rudd has advocated for a soft Brexit modelled on the deal the EU has with Norway.
"The PM has my full support," she said earlier today.