Lib Dem leader Ed Davey describes the prime minister's "attempt to apologise" as "shameful".
He asks why the only person to resign over the issue so far is Allegra Stratton - a senior government spokeswoman who stepped down after a video showed her joking about No 10 staff holding a lockdown Christmas Party at Downing Street.
By contrast, Davey points out that Boris Johnson - "who sanctioned and attended at least one party in No 10" - remains in post.
"Will he accept that the party is over and decide to resign?" he asks.
The prime minister again asks people to wait and see what the ongoing inquiry says.
Stafford and Stone Liberal Democrats petition poster