BORIS Johnson appears to be teetering on the edge as he desperately scrambles to save his premiership.

His government has been engulfed by reports of rule-breaking parties on Downing Street, with the Prime Minister’s half-baked apologies doing little to appease the public.

Backbench Tory MPs have now launched a serious challenge to his leadership, with dozens believed to have submitted letters of no confidence.

Such is the outrage that one Conservative MP jumped ship and joined Labour, taking his seat on the opposition benches before PMQs.

WATCH: Boris Johnson laughs at Ian Blackford's question and refuses to resign

But if Johnson does go, who is likely to replace him?

Rishi Sunak

The National:

Chancellor Rishi Sunak is the bookies’ favourite on 7/4, according to comparison site Oddschecker.

Sunak has been noticeably muted in his defence of Johnson throughout the partygate scandals, prompting some to speculate he is eyeing a leadership bid.

The potential successor as Tory leader abruptly ended an interview on Tuesday when pressed if he gives his full support to the Prime Minister.

Liz Truss

The National:

Foreign Secretary Liz Truss is the Chancellor’s closest rival, according to bookmakers.

The minister has been embroiled in her own scandal this month, after it was alleged she overruled civil servants’ advice to host a £3000 lunch for a US trade representatives at a members’ club in Mayfair.

Jeremy Hunt

The National:

Jeremy Hunt, a former party heavyweight exiled by the Johnson administration, is the third favourite.

The former foreign and health secretary, who lost out to Johnson in the 2019 leadership contest, said this week his ambition to become PM has not “completely vanished”.

Michael Gove

The National:

The aforementioned trio are well ahead of the rest of the pack in the bookies’ estimations.

One possible candidate who could break from the pack is Michael Gove, who famously turned on Johnson during the 2019 contest in a surprise bid to land the top job.

The Scot, however, remains a rank outsider.

Who do you think will succeed Boris Johnson as Tory leader?