One Labour source said their jaw was "on the table at how damaging this is for the Tories" following the debate, with others describing it as a "generous gift" for Sir Keir Starmer.
"Alice in Wonderland. We’re in for even more serious trouble if this woman becomes PM. Cynical beyond belief. "
“We need to capitalise on these opportunities by ditching the mass of unnecessary regulations and low-growth mentality we’ve inherited from the EU.
Mr Sunak is the frontrunner in the Conservatives’ leadership race, with 101 votes in the second ballot, but the mistake drew ire from some on Twitter.
"This is SO good," wrote Stewart Reynolds after watching the parody video, which could end up being essential viewing for future Tory candidates!
‘That man should be publicly horse-whipped once a week, every week, touring round cities and towns in the UK," said Mark Thomas.
"Trump packed the supreme court, with disastrous results. Now Johnson is trying to do the same to our House of Lords."
The Conservatives’ choice of the next prime minister will be announced on September 5.
It comes as Rishi Sunak and Penny Mordaunt have maintained their places at the front of the Tory leadership race as Suella Braverman was eliminated.