Northern Ireland’s First Minister Paul Givan said the public have not accepted Boris Johnson’s claim that he believed the Downing Street gathering was a work event.
“I don’t think the public accepted that justification, if it was an attempt to justify that this wasn’t a party and that it was work-related,” he said.
“So ultimately, Boris Johnson needs to be able to convince the general public, he also needs to be able to convince his own party.
“It is they who will decide the future of the Prime Minister. Either he takes a decision himself around his future or it’ll be the Conservative Party that will take that decision.
“And this report, I think, is going to be very important, which Sue Gray is responsible for.
“I think there is an imperative for that work to come to a conclusion so that we can all draw a line under this and ensure that the wider public health messaging is consistent, rather than being distracted by what’s going on at Downing Street.”
Top Stormont civil servant Sue Gray,who returned to London from Northern ireland to take up a post in the Cabinet Office, has been tasked with leading the inquiry into lockdown parties.
The DUP is the only Westminster party not calling for the resignation of Boris Johnson despite the Tory prime minister double crossing them on the Northern Ireland protocol.
The DUP said it will wait for the outcome of an inquiry into Covid rule-breaking at 10 Downing Street amid claims there is a "split" in the party over hopes the beleaguered Prime Minister will eventually "deliver" on the protocol.
Pressure mounted on the PM as he apologised to MPs for attending a drinks party in the Downing Street garden in May 2020.
Mr Johnson said he believed the gathering was a work event, but a leaked email shows an invite to the "bring-your-own-booze" meet-up was sent to up to 100 people.
As calls mounted for the Prime Minister to resign - including from Tory MP William Wragg, who is vice chair of the Conservatives' influential 1922 Committee of backbench MPs - the DUP is alone in not calling for Mr Johnson to step down.
In November 2018 Mr Johnson attend the DUP annual conference and told the lead unionist party that he would never put a border in the Irish Sea. In October 2019, as Prime Minister, he agreed a deal with Taoiseach Leo Varadkar which did just that.
"Those who make the rules should not only abide by them but should be seen to do so," a DUP spokesman said last night.
"The events in and around Downing Street have been disgraceful, distressing and disturbing in equal measure, particularly to everyone who followed the law. All these revelations have caused damage to the standing of the Prime Minister and his government. His explanation begs more questions than it answers and certainly underscores the fact that the Downing Street operation is broken."
However, he added: "We will await the outcome of the independent inquiry which is likely to be published shortly and which will have a critical bearing on reporting all the facts."
Political commentator Brian Feeney said the refusal to call for Mr Johnson to quit showed that some in the DUP still had faith in him, despite his implementation of the NI Protocol against their wishes.
"The DUP is split with what response it should have here. Some would prefer to get rid of Boris Johnson, but others hang on in the desperate hope that he will deliver for them on the Protocol," Mr Feeney said.
"Just a few days ago Jeffrey Donaldson went to Liz Truss to ask for a deadline for action on the Protocol, yet on Tuesday Secretary of State Brandon Lewis said there would be no arbitrary deadline while on a visit to Kilkeel."
He added: "I think the DUP will find it difficult to get a unified line on this issue."
