Jo Swinson launched a highly personalised attack on Boris Johnson as she accused him of being “not fit” to be Prime Minister.
The Liberal Democrat leader used a keynote campaign speech in London to attack Mr Johnson over his sense of “Etonian entitlement”.
Ms Swinson accused the PM of not caring about jailed British-Iranian mother Nazanin Zaghari-Ratcliffe.
“Boris Johnson only cares about Boris Johnson,” she said.
“He will do whatever it takes, sacrifice whatever or whoever is needed to get what he wants.
“His life has been about becoming prime minister. Not out of some burning desire to make people’s lives better, but out of some sense of Etonian entitlement, because it’s what people like him get to do.
“Boris Johnson doesn’t care about you and your family.
“Just take the case of Nazanin Zaghari-Ratcliffe – a British mother wrongfully imprisoned, a small child devastated, separated from her mum.
“When he was talking about that case, his words would be used against Nazanin at her trial.”
Ms Swinson insisted Mr Johnson was “not fit” to be Prime Minister after “lying to the Queen” over temporarily suspending Parliament.
She also highlighted the endorsement pf the PM by English Defence League founder Tommy Robinson.
“Boris Johnson is not fit to be Prime Minister. not just because he doesn’t care, not just because he lies, but also because he is complicit in stoking division and fear in our communities.
“Why else would Britain’s biggest racist, Tommy Robinson, be supporting him?
“Honestly – such an endorsement would shame any decent person but Boris Johnson has no shame when it comes to the language he uses about race.”
Ms Swinson compared the PM to US President Donald Trump.
She said: “Now we have our own ‘Britain Trump’ – Boris Johnson.
“Whether it is the sexist, patronising crap of comparing elite women athletes to wet otters, or him bragging about patting his female boss on the bottom … this man isn’t someone our sons can look up to, that our daughters can have faith in.
“Boris Johnson is not fit to be Prime Minister.”
When it was put to her that Mr Johnson refuses to say how many children he has, Ms Swinson said: “I have two children, by the way.”
Ms Swinson tried to put a positive gloss on a poll showing that the Lib Dems may only gain one seat at the election.
She said: “What this poll shows is that there are 134 seats where either the Liberal Democrats are in first or second place as things stand.
“That shows there’s a huge amount to play for.”