How will a new UK PM be chosen?

STORY: Boris Johnson has resigned, triggering the search for a new British prime minister.

But how will a new premier be chosen?

Candidates who wish to make a bid for the leadership - of which there could be many - must be nominated by at least two other Conservative lawmakers.

Those lawmakers then hold several rounds of voting in a secret ballot to whittle down the field.

Each time, the person with the fewest votes is eliminated.

This process is then repeated until there are just two candidates remaining.

The final two are then put to a postal ballot of the wider Conservative Party membership, and the winner will be named the new leader - and the de facto prime minister.

Although he or she does not have to call a snap election, they do have the power to do so.

So how long could all this take?

The duration of a leadership contest can vary, and depends on how many people put themselves forward.

Johnson himself faced former health minister Jeremy Hunt in the run-off ballot of Conservative members to replace outgoing Theresa May in 2019 - and took office two months after she announced her intention to resign.

This time around, the process could be accelerated before parliament takes its six-week summer recess from July 21.

Votes have previously been held every Tuesday and Thursday.

It’s too early to predict who will replace Johnson, but there are some lawmakers likely to take a shot at the top job.

Foreign minister Liz Truss, a favorite of the ruling Conservative Party’s grassroots, has regularly topped polls of party members carried out by website Conservative Home in the past.

Hunt could take a second punt at the premiership, and would offer a less controversial style of leadership - something that could be welcomed after the party's recent turmoil.

Former finance minister Rishi Sunak, one of the first to resign from Johnson’s government this week, is also likely to run.

As could his newly-appointed replacement Nadhim Zahawi, who was in the job just hours before calling on his boss to resign.