* Johnson accused of breaking his own COVID rules
* Opponents say he should resign over Downing St party
* PM's lawmakers say he must come clean
* Papers ask whether the party is over for Johnson (Adds Conservative lawmakers)
By Michael Holden and Elizabeth Piper
LONDON, Jan 12 (Reuters) - British Prime Minister Boris Johnson will have to fight on Wednesday to defend his premiership amid demands from across the political divide to come clean about a "bring your own booze" party held in Downing Street during a coronavirus lockdown.
Opposition lawmakers have called for Johnson to resign and some in his own Conservative Party have said he should quit if he is found to have broken strict laws his government brought in to prevent the spread of the virus.
Johnson, who won a landslide 2019 election victory on a promise to secure Britain's exit from the European Union, has so far refused to say whether he attended the gathering at his official residence, 10 Downing Street, on May 20, 2020.
"His survival is in the balance at the moment," said one senior Conservative lawmaker, speaking on condition of anonymity due to the sensitivity of the situation.
"He has got to make a clean breast. I usually find that if you make your apologies, it defuses the issue. Can't have it hanging on."
The prime minister and his partner Carrie mingled with about 40 staff in the Downing Street garden after his Principal Private Secretary Martin Reynolds sent an invitation by email using the pronoun "we", ITV News reported.
Johnson's spokesman has repeatedly refused to comment on the details of the report.
When Johnson fields questions from lawmakers in parliament on Wednesday at 1200 GMT, there is just one issue they will demand an answer to: was he at the drinks party or not?
"How do you defend the indefensible? You can't!," Conservative lawmaker Christian Wakeford wrote on Twitter. "We need openness, trust and honesty in our politics now more than ever and that starts from the top!"
Newspapers, including those which are usually very sympathetic to Johnson, warned that unless he resolved the issue, his position could become untenable.
On its front page, the Daily Mail posed the question many commentators were asking after the recent scandal: "Is the party over for PM?"
Two snap polls on Tuesday showed well over half of respondents thought Johnson should resign.
But his biographer Andrew Gimson said he was unlikely to quit unless forced by his parliamentary colleagues.
"He will be looking for a way through this. He is not the resigning type," Gimson said.
LOCKDOWN PARTY?
"If he has lied to the British public and lied to parliament and attended parties during lockdown then his position is untenable," the main opposition Labour Party's deputy leader Angela Rayner said.
"Many people who lost loved ones over that period and were not able to see them are devastated by this news that Number 10 was partying while their loved ones died alone. This is completely unacceptable."
Since details of the gathering emerged, Johnson has simply said he cannot comment until a senior government official, Sue Gray, concludes an internal investigation into other allegations that Johnson and his officials held rule-breaking parties.
Just two years after Johnson's election triumph, and less than six after he led the Brexit campaign to victory in 2016's EU referendum, speculation about his leadership is rife.
There are mutterings that Conservative lawmakers, who can trigger a leadership challenge if 54 of the 360 in parliament write letters of no confidence, are sharpening their knives.
Last month, the Conservatives lost a parliamentary seat they had held for almost 200 years while the party's comfortable lead over Labour in opinion polls has also evaporated.
A series of mis-steps and scandals https://www.reuters.com/world/uk/sleaze-scandal-lockdown-parties-trying-times-uk-pm-johnson-2022-01-11 and public anger over the government's handling of the COVID-19 pandemic, rising energy bills and concerns about surging inflation have fuelled Conservative unease.
Johnson has previously told parliament that all COVID-19 guidance had been followed, no rules had been broken and that there had been no party at his residence.
"It's not blowing over," Conservative lawmaker Tobias Ellwood told Sky News. "We can't allow things to drift, that is not an option."
(Additional reporting by William James and Kylie MacLellan; Editing by Guy Faulconbridge and Catherine Evans)
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