Former Prime Minister Major calls Johnson hypocritical because he would like to take the House of Commons offside while he has always sold the brexit as a way for parliament to gain more power.
At Prime Minister's Questions, Theresa May said the ambassador's resignation was "a matter of deep regret".
Johnson, who has said leaving the European Union by the scheduled date of October 31 is a "do or die" matter, refused to rule out bypassing Parliament to prevent lawmakers from blocking a no-deal departure. "They made that sacrifice so we could create a better world and we have".
Nicola Lowery said it was important the next PM delivers a "collective vision" in parliament, and that Johnson was the man to do it.
Ms May underscored she had done all she possibly could to try to get her Brexit deal approved and did nothing to hide her frustration with the fact that some of her most strident opponents on Brexit are those now backing Mr Johnson.
A spokesman for Johnson did not immediately respond to a request for comment. Johnson and Hunt braced for the release of a grilling by the BBC's Andrew Neil as the Conservative leadership contest begins to draw to a close.
It comes after Daily Star Online reported Boris had state secrets kept from him because he couldn't be trusted while he was Foreign Secretary.
Johnson is the favourite to become the next prime minister. According to him, Johnson lacks the leadership qualities to do that. A member of her inner circle said Mrs May was "furious" about his resignation.
Conservative writer Tim Montgomerie said: "I attended many events at the UK Embassy in Washington - they were packed with establishment Clintonians".
Jo Churchill MP is being blamed for a defeat that could allow MPs to block a no-deal Brexit after she forgot to cast her vote, The Times has reported.
"On the other side, people who said they didn't want to leave with no deal, but weren't prepared to vote for a deal in order to make sure that what they wanted happened".