UK's Johnson ends bid for comeback as PM

Britain's Boris Johnson on Sunday dramatically ended an audacious bid to return to power within weeks of having been ousted, announcing he would not run to replace outgoing leader Liz Truss.

The surprise decision, which the ex-premier said had been reached reluctantly after recognising he would not lead "a united party in parliament", removes a major obstacle to his political foe, former finance minister Rishi Sunak, becoming leader.

That could now happen as soon as Monday.

Johnson, 58, said he had reached out to both Sunak and cabinet member Penny Mordaunt -- who launched her leadership campaign on Friday -- to "come together in the national interest".

But the three of them had "not been able to work out a way of doing this", he added.

"Therefore I am afraid the best thing is that I do not allow my nomination to go forward and commit my support to whoever succeeds," he said in a statement.

"I believe I have much to offer but I am afraid that this is simply not the right time."

Earlier Sunday, Sunak formally announced he was standing for the top job, just weeks after having failed in a first attempt.

The former finance minister vowed "integrity, professionalism and accountability" and to lead Britain out of "profound economic crisis".

"I want to fix our economy, unite our party and deliver for our country," he said in a short statement posted on Twitter confirming his widely expected candidacy.

The Tories have been forced into a second, this time expedited, leadership contest since the summer following Truss's resignation after only 44 disastrous days into her tenure over her calamitous tax-slashing mini-budget.

Johnson had cut short a Caribbean holiday to return to Britain Saturday to try to stage a political comeback less than two months after leaving office.

He was reportedly lobbying Conservative colleagues ahead of a Monday afternoon deadline to secure the 100 nominations required to face a vote of the Tories' 357 MPs.

In his statement, he said he had met the threshold by gathering 102 nominations, after being "overwhelmed by the number of people who suggested that I should once again contest the... leadership".

There was "a very good chance" he could win the race -- to be decided by the approximately 170,000 party members this week if a run-off is held.

"But in the course of the last days I have sadly come to the conclusion that this would simply not be the right thing to do," he added.

"You can't govern effectively unless you have a united party in parliament."

Johnson, who only relinquished power in early September following a government revolt over a slew of scandals, is still seen as the grassroots' favourite.

Sunak had raced ahead in the count for Tory MPs' support, drawing backing from across the parliamentary party and crossing the minimum threshold Friday.

He currently boasts the public backing of 146 Tory lawmakers, according to a BBC tally. The publicly declared support for Johnson ran at 57, and 23 for Mordaunt.

Johnson's attempt at political resurrection, while drawing significant cabinet and party backing, had also stirred opposition within his own party.

"This isn't the time for Boris," Sunak-supporting Northern Ireland minister Steve Baker told Sky News, arguing another Johnson-led government "would be a guaranteed disaster" and implode within months.

Johnson and Sunak held talks late into Saturday night, reports said.

The ex-leader also reportedly spoke on Sunday to Mordaunt, who was said to have rebuffed his calls to back him, noting her supporters were likely to split more for Sunak.

Mordaunt, 49, who missed out on the last contest's run-off by just eight MPs' votes, will now come under pressure to concede rather than force the contest to a vote of members.

Following Johnson's announcement a campaign source said she would remain in the race.

"Penny is the unifying candidate who is most likely to keep the wings of the Conservative Party together," the source told UK media.

"Polling shows that she is the most likely candidate to hold onto the seats the Conservative Party gained in 2019."

New polling suggested the Tories could benefit from a change of leader, after Truss's missteps plunged them to unprecedented lows.

But a survey by Conservative pollster James Johnson still found the remaining Tory candidates both have negative favourability: Mordaunt -15 and Sunak -2.

The main Labour opposition, which has opened up huge poll leads, is demanding a general election.

"The country needs to get rid of this chaos," its leader Keir Starmer said.