British Prime Minister Boris Johnson issued an apology Wednesday for attending a party during the country's COVID-19 lockdown in 2020, but ignored the opposition's calls for his resignation.

Johnson is facing a tide of anger from the public and politicians over claims he and his staff flouted pandemic restrictions by socializing when it was banned. Some members of his Conservative Party have joined in the criticism, saying he must quit if he can’t quell the furor.

Johnson acknowledged for the first time Wednesday that he went to a May 2020 garden party at his Downing Street office, though he said that he had considered it a work event to thank the staff for their efforts during the pandemic.

"I want to apologize. ... With hindsight, I should have sent everyone back inside," Johnson told lawmakers in the House of Commons.

Opponents and allies alike have been demanding Johnson come clean about the "bring your own booze" party, held when Britain was under a strict lockdown imposed by Johnson to curb the spread of the coronavirus.

An invitation to the "socially distanced drinks" gathering was emailed to about 100 people by a senior prime ministerial aide. At the time, people in Britain were barred by law from meeting more than one person outside their household.

Johnson’s lunchtime appearance at the weekly Prime Minister’s Questions session in the House of Commons was his first public appearance since details of the party emerged.

The prime minister struck a tone of contrition but urged people to await the conclusions of an investigation by senior civil servant Sue Gray into several alleged parties by government staff.

Opposition Labour Party leader Keir Starmer said Johnson's statement was "the pathetic spectacle of a man who has run out of road.

"His defense ... that he didn’t realize he was at a party is so ridiculous that it’s actually offensive to the British public," Starmer said. "He’s finally been forced to admit what everyone knew, that when the whole country was locked down he was hosting boozing parties in Downing Street. Is he now going to do the decent thing and resign?"

Johnson declined to resign, but said he understood the rage of people who "have made extraordinary sacrifices over the past 18 months."

"I understand the anger, the rage that they feel at the thought that people in Downing Street were not following those rules," Johnson said – though he didn't explicitly admit that he had broken any rules.

He said opponents should await "the full conclusion of the inquiry until the full facts are brought before this house." Gray is due to report her findings by the end of the month.

The scandal dubbed "partygate" adds to a mounting list of troubles for Johnson.

During the U.K.’s first lockdown, which began in March 2020 and lasted for more than two months, almost all gatherings were banned. Millions of people were cut off from friends and family, and even barred from visiting dying relatives in hospitals. Thousands were fined by police for breaking the ban on gatherings.

So there has been widespread anger at claims Johnson’s Conservative government flouted the rules it had imposed on the rest of the country by holding garden parties, Christmas get-togethers and office quiz nights in Downing Street, which is both the prime minister’s home and his office.

In Parliament on Wednesday, a string of opposition lawmakers accused Johnson of lawbreaking, lying and debasing his office.

He can shrug off those criticisms since his Conservatives have an 80-seat majority in the House of Commons. More worryingly for the prime minister, however, many members of his own party are increasingly concerned about Johnson’s judgment and leadership.

The Conservatives picked Johnson as leader in 2019 for his upbeat manner and popular touch, and despite the serial allegations of rule-bending and dishonesty that have followed him through his twin careers as journalist and politician. The choice appeared vindicated when he led the party to a big election win in December that year.

But support inside the party is being eroded by discontent over continuing pandemic restrictions, which some Conservatives view as draconian. He is also facing disquiet about his judgment after a slew of financial and ethical misconduct allegations against him and his government.

The Conservatives have a history of ousting leaders if they become a liability – and a recent surprising loss in a by-election for a district the party held for more than a century has increased their jitters.

Conservative legislator Christian Wakeford urged Johnson not to "defend the indefensible."

"It’s embarrassing and what’s worse is it further erodes trust in politics when it’s already low," Wakeford wrote on Twitter. "We need openness, trust and honesty in our politics now more than ever and that starts from the top!"

Another Conservative lawmaker, Tobias Ellwood, said Johnson needed to apologize and "show some contrition" if he wanted to ride out the storm.

"We can’t allow things to drift, that is not an option," he told Sky News.