Jeremy Corbyn has said he is daunted by the prospect of being the next prime minister, but says he would be ready to take on the role if he won an election.
In a BBC interview, he said he would be “utterly determined” to carry Labour’s programme into government.
He also said it was “improper” for the Queen to be asked to get involved in the Scottish independence referendum.
His comments follow ex-PM’s David Cameron’s revelation that he sought the monarch’s help ahead of the 2014 poll.
The next general election is due to be held in 2022, but Prime Minister Boris Johnson wants an early election to break the Brexit deadlock.
Under the Fixed-term Parliaments Act, the prime minister could call a general election if two-thirds of MPs vote for one.
However, Mr Johnson was defeated on this twice in Parliament earlier this month.
Mr Corbyn said the UK “needs” a general election, but his “priority” was to work towards blocking a no-deal Brexit, with an election afterwards.
When asked if he was ready to be prime minister in a few weeks’ time if needs be, Mr Corbyn said: “Yes. Absolutely.”
Asked if he was daunted by this prospect, he replied: “Yes.”
He said he was “utterly determined to carry through into government our programme to bring about better social justice across this country, the environmental aims that we’ve got and to provide hope particularly for young people in our society”.
Commenting on reports that he would stay neutral on Brexit, Mr Corbyn said: “I’m not neutral. What I’m saying is the British people must have a chance to decide the end of this process.
“We’ve had a referendum in 2016, we’ve had all the debate and we now have a PM trying to take us over a cliff-edge in a few weeks’ time. That’s entirely wrong.
“That’s why I did all I could to work with opposition parties to legislate to ensure that he had to negotiate an extension.”
This law requires the prime minister to ask for an extension to Article 50 – the process by which the UK leaves the EU – if Parliament has not approved either a deal or a no-deal Brexit by 19 October – the day after a two-day EU summit.
If Labour wins an election, Mr Corbyn has said he will hold a referendum that offers a “credible” Leave option and Remain.
Mr Corbyn continued: “I want to put to the British people a credible offer of Remain – hopefully with reform to the EU – or Leave with a trade deal, a customs deal and protection of the environment, consumer, workers’ rights and protection of the NI peace deal.”
His comments come ahead of Labour’s conference, where Mr Corbyn is expected to face increasing pressure to back Remain.
Mr Corbyn’s approach is at odds with Tom Watson, the party’s deputy leader. Mr Watson says reversing Brexit, through another referendum, should take priority over winning power in a general election.
And on the revelation that Mr Cameron asked whether the Queen could “raise an eyebrow” about the prospect of Scotland voting for independence, Mr Corbyn said this was “improper”.
“I don’t think she should be asked to be involved in political decisions,” Mr Corbyn said.