The PM and the Labour leader will be grilled by the public in a Sky News interview this evening live from Grimsby.
Sunak has hit back at claims that his party had already conceded defeat in the vote on July 4.
Asked by reporters on the Tory battle bus if he had given up on winning the election, Sunak said: “No, absolutely not.
“What you saw yesterday is we put the manifesto forward which has got a very clear set of tax cuts for the country, tax cuts at every stage of your life.
“Whether you’re working, setting up a small business, tax cuts when you’re trying to buy your first home, tax cuts for pensioners, and tax cuts for families.
“And I’m really energised to now have a chance to put our very clear plan to the country.”
He added: “I’m always pumped. When am I not? You’ve seen me.
“I’m fuelled by enormous amounts of sugar. It’s hard not to be pumped between my Haribos and my Twixes and everything else.”
Sky News‘ The Battle For Number 10 will be live tonight from 7pm in Grimsby – a key battleground constituency for the election.
Watch our daily politics show
Watch The Sun’s new DAILY Never Mind the Ballots Election Countdown show on our brand new YouTube channel here.
Every weekday Sun Political Editor Harry Cole brings you the latest news and analysis from the election campaign trail.
This morning Defence Secretary Grant Shapps had warned voters against handing Labour a “super majority” – appearing to hint that he thinks his party will not win the most seats.
He blasted that the “country doesn’t function well” when either party has a three-figure majority in the House of Commons.
Mr Shapps insisted the Tories were still fighting for “every seat” and “no one’s cast a vote” as the election campaign hits the halfway stage.
Speaking to Times Radio, he said: “You want to make sure that in this next government, whoever forms it, that there’s a proper system of accountability.
“You don’t want to have somebody receive a super majority.
“And in this case, of course, the concern would be that if Keir Starmer were to go into No.10 and that power was in some way unchecked.
“It would be very bad news for people in this country… A blank cheque approach, allowing (them) to do anything they wanted, particularly when their particular set of plans are so vague.
“They say change, but you’ve no idea what they actually want to change to, other than the fact that they’d outlined plans which would cost £2,094 to every working family in this country.
“If you ended up with a party with a massive majority, unchecked power, able to do anything that they wanted.
“With the instincts of… Keir Starmer’s party on all sorts of things, from raising people’s tax to their lack of support for increased defence spending, we think that would be a dangerous place to put this country.”
The most recent polling has suggested that Labour could be on course to win a majority bigger than that secured by Tony Blair in 1997.
A poll released by YouGov last night put Labour on 38 per cent, with the Tories on 18 per cent and Reform only one point behind on 17 per cent.