Keir Starmer has said he is “sure” Durham Police will decide he did not break lockdown rules.
The Labour leader has pledged to resign if issued a fixed penalty notice over the so-called beergate row.
Police are investigating whether Starmer broke the law by eating curry in an MP’s office with staff after a day of campaigning for the local elections in April 2021.
In an interview with ITV’s Loose Women on Monday, the Labour leader said he had put “everything on the line” because it was the “right thing to do”.
Starmer said the accusation made against him was entirely different from the “industrial rule breaking” taking place in Downing Street.
Boris Johnson has already been issued one fine for breaking his own Covid rules, but has rebuffed demands that he step down as prime minister.
“I’m very clear I haven’t broken the rules,” Starmer said. “But equally I’ve said if the police do issue me with a FPN I will do the right thing and I will step down.
“I’ve put everything on the line because I think that’s the right thing to do. That’s the complete opposite of the prime minister.”
He added: “I haven’t broken the rules. I am sure that’s going to be the finding.”
Starmer found out Durham Police had reopened its investigation into him on Friday May 6, as he was celebrating local election victories.
It was not until Monday that he called a press conference to announce his intention to quit should he be fined.
But he told ITV it was his “instinct” to make that move “as soon” as the police made their announcement.
“In my heart I knew what I was going to say,” he said. “There was no way I wasn’t going to say that.”
“As soon as I knew there was a reinvestigation, I knew I was going to say that because that was so deep down inside me as to what I believed.”
It is still not clear if Starmer would quit if police find he had breached the rules but do not issue a fine.
At the time of the event, the ban on indoor mixing between households remained in place.
But there was an exemption for “work purposes”, and Labour has said Starmer simply legitimately took a break from work to eat.