Who could become UK's new PM?

Here are the main contenders potentially in the running to succeed UK Prime Minister Liz Truss, after she announced her resignation on Thursday:

Rishi Sunak 

Truss easily beat the former chancellor of the exchequer in this summer's Tory leadership contest, winning party members over with promises to slash taxes and regulations without curbing government spending. Rishi Sunak

Sunak, 42, had warned that her plans to fund the proposals through extra borrowing were reckless and could worsen decades-high inflation as well as market confidence in the UK.

Now that he has been proved right, Sunak was installed by bookmakers as the early favourite following Truss's dramatic announcement.

He garnered the support of the largest number of Tory lawmakers in successive rounds of voting, before party members installed Truss.

A new YouGov poll on Tuesday found he has the best ratings of the touted alternatives to Truss -- albeit still with an overall net favourability rating of -18.

But he is also now viewed as a divisive figure.

Many party members, who usually get the final say on who leads the party, are unwilling to forgive him for his role in ousting ex-prime minister Boris Johnson.

Boris Johnson 

The former premier left office early last month after a revolt among his cabinet and Tory MPs, sparked by the resignation of Sunak and others from his faltering government following months of controversies.

Encouraged by several strong hints from Johnson himself, speculation has swirled ever since that he would attempt an eventual comeback -- though few thought that could be feasible this quickly.

The Times reported after Truss's demise that he was planning to enter the race.

The ever-ebullient Brexit figurehead remains popular with a section of Conservative MPs and the party. But his brand among the wider electorate was severely damaged by his scandal-tainted three-year tenure.

A recent YouGov poll showed the 58-year-old is far more popular than Truss. Yet around two-thirds of those asked had an unfavourable opinion of him.

Johnson has kept a low profile since resigning, giving a paid speech in the United States last week but no indications of his views on the current crises gripping the UK.

He was thought to favour Truss in the summer leadership contest -- although his former top aide-turned-arch-critic Dominic Cummings argued that this was because he expected her tenure to be disastrous and short-lived, paving the way for his return.

Ben Wallace 

Wallace has impressed as defence minister, with Britain playing a pivotal role in the global response to Russia's invasion of Ukraine.

Popular with members, it came as a surprise when the former army captain opted not to enter the race to replace Boris Johnson over the summer, saying he "didn't want it enough".

But asked at the recent Conservative party conference if he would consider running, the 52-year-old said: "I don't rule it out."

In the most recent survey of Tory activists by website ConservativeHome, Wallace scored a net approval rating of 85.8 points, far ahead of any potential rivals.

While a soldier, Wallace led a patrol that captured an IRA unit attempting to carry out a bomb attack. He was also part of the team that brought home the body of Princess Diana following her car crash in Paris.

Penny Mordaunt 

The current cabinet member, 49, was an early grassroots favourite to succeed Johnson, and came within eight MPs' votes of beating Truss to make the final run-off against Sunak.

The former defence and trade minister was a strong Brexit supporter and key figure in the 2016 "Leave" campaign.

But she faced criticism in the recent leadership race, some MPs accusing her of being ineffective in previous government roles.

Mordaunt's profile rose this week after she was sent out on Monday in place of Truss to answer an urgent question in parliament from the Labour opposition about the recent economic turmoil.

Despite being forced to explain that the prime minister was "not under a desk" -- in response to accusations that Truss was in hiding -- Mordaunt was seen to have coped well with a febrile House of Commons.

Among other potential runners, new finance minister Jeremy Hunt and former cabinet heavyweight Michael Gove were both said to have ruled themselves out.