Video report by ITV News Political Correspondent Carl Dinnen
Boris Johnson said parliament's failure to pass a Brexit deal left him with "no choice" but to call a general election.
Speaking outside Number 10 at the formal start of the election campaign, Mr Johnson said the inability to break the impasse among MPs left him wanting to "chew my own tie".
His speech outside Downing Street was delayed after Welsh Secretary Alun Cairns resigned over allegations he knew a former aide "sabotaged" a rape trial - something Mr Cairns has denied.
Mr Johnson told reporters: “I want you to know of course it that I don’t want an early election and no one much wants to have an election in December, but we’ve got to the stage where we have no choice because our parliament is paralysed, it’s been stuck in a rut for three and a half years.
“And I’m afraid our MPs are just refusing, time and again to deliver Brexit and honour the mandate of the people.
“I can tell you, I’ve got to the stage where I’ve been wanting to chew my own tie in frustration because, in a sense, we’re so nearly there.
“We’ve got a deal, oven ready, by which we can leave the EU in just a few weeks.”
Mr Johnson used the speech to pitch his brand of Conservatism to voters, praising the proposed investment in the NHS and policing.
He urged voters to back his Conservative Party to get Brexit over the line, insisting a vote for any of the smaller parties would lead to a "technicolour" government led by Jeremy Corbyn which could reverse Brexit.
He also warned that a vote for Labour could lead to the break-up of the UK, adding it could open the door for another referendum on Scottish independence.
Mr Johnson said: "And what is his plan for that renegotiation? What question would be put to the public? We don't know. What are the options? We don't know.
"We don't even know what side he would take, and we don't know what would happen if the result was either for remain or for leave."
He added: "What we do is that in any scenario, the dither and the drift, and the delay, which is increasingly damaging for our country, would just continue."
Mr Johnson added: "If I come back here with a working majority in Parliament then I will get Parliament working again for you.