Keir Starmer claims he only said Corbyn would be a 'great PM' in 2019 because he was 'certain Labour would lose' as he squirms on tax hike plans in crucial Sky News election grilling - with Rishi Sunak waiting in the wings for his turn

Keir Starmer insisted he only backed Jeremy Corbyn in 2019 because he knew he would not win as he kicked off a crucial TV election grilling tonight.

The Labour leader was challenged on why he now condemns his left-wing predecessor after arguing he would make a 'great PM' five years ago.

Sir Keir wriggled as he was asked on Sky News how people could 'trust' him, arguing that he only endorsed Mr Corbyn because he was 'certain that we would lose'. 

He also squirmed as he was pushed by presenter Beth Rigby on whether he would rule out all tax rises - sticking to his line that income tax, national insurance and VAT would not be touched. He would not completely deny that council tax or fuel duty could increase. 

As the campaign reaches the halfway point, the Labour leader and the PM will both be interrogated and face questions from a live studio audience in Grimsby.

Allies are hoping the programme could be a turning point for Mr Sunak, who is trailing far behind in the polls and under threat from Nigel Farage's Reform.

Mr Sunak is commentating on Sir Keir's turn on social media afterwards, to underline the fact the Labour leader would not go head-to-head again.

He swiped: 'Does anyone know what Keir Starmer actually stands for?' 

Pressed on his shifts in position over core issues, Sir Keir was asked whether there was a trust issue.

He said: 'No because what I would say is this – I decided it must be country first so every decision after that I judged previous decisions, previous positions and I said 'Is this truly country first, party second'; if the answer to that was 'no' then I changed the position and dragged my party back to the service of working people.'

On his previous support for Mr Corbyn, Sir Keir said: 'I was certain that we would lose the 2019 election.'

He added: 'I did campaign for Labour, of course I did, I will openly say I campaigned for Labour, I wanted good colleagues to be returned into the Labour Party.'

Sir Keir repeatedly said he was 'certain' Labour would lose in 2019 when challenged over his support for Mr Corbyn.

Sir Keir was given a round of applause as he insisted: 'The Tories are in no position to lecture anyone about tax rises.

But he struggled on the detail of his own proposals, after Mr Sunak demanded he match Tory vows to rule out tax increases. 

'We've got the highest tax burden for 70 years and I think working people shouldn't pay more tax. We will not raise their tax.

'What we need to do is get the economy going – there's a reason that taxes have gone up so much in recent years and that's because the economy is flatlining.'

The clashes come after another difficult day on the campaign trail for Mr Sunak. He had apologised for coming back early from D-Day commemorations last week to do an ITV interview, but footage has emerged showing him apologising that the events 'ran on'. 

He also told the broadcaster that hardship in his childhood was going without Sky TV so his parents could afford to send him to elite public school Winchester. 

Some Tories are nervous that Mr Sunak is showing a propensity for blunders, with one gloomily observing it seems like 'everything he touches turns to sh**'. 

The party veteran suggested Mr Sunak was in a doom loop where 'nothing is a gaffe for Labour and everything is a gaffe for the Tories'. 

The Conservative website previously featured a big photo of Mr Sunak with a button asking voters to 'join Rishi'. However, since the manifesto launch yesterday his images are much less prominent.

A YouGov survey today laid bare the scale of the task Mr Sunak faces, with Labour 20 points ahead. Sir Keir's outfit were supported by 38 per cent of voters, with the Conservatives on just 18 per cent.

The Tory vote share was the joint lowest since 2019 and only one point ahead of Reform UK (17 per cent) and three points ahead of the Lib Dems (15 per cent).

The PM is expected to hammer home his tax-cutting plans on the Sky News programme this evening, after unveiling the Conservative manifesto yesterday.

If he stays in power, he has promised to oversee another 2p cut to National Insurance to reduce the tax to 6 per cent by April 2027.

The PM also pledged that NICs will be abolished altogether for four million self-employed over the next Parliament, as part of his £17billion of tax cuts.

Last week's ITV debate between Mr Sunak and the Labour leader saw the political rivals clash over tax in fiery head-to-head exchanges.

Labour figures were left fuming at the PM's 'lies' about their tax plans, after Mr Sunak berated Sir Keir for plotting to hike the tax burden for Brits by £2,000.

The PM was dealt a blow ahead of tonight's Sky News programme as the UK economy was shown to have flatlined in April, according to latest figures.

The Office for National Statistics reported that growth domestic product (GDP) was flat during the month following growth of 0.4 per cent in March.

The data will present a headache for the PM, who told voters the economy had 'turned a corner' after it emerged from recession in the second half of last year.

Mr Sunak is also facing a fresh row over D-Day after it was revealed how he blamed the late-running commemoration events for his delayed arrival to a TV interview.

The PM has suffered days of outrage after he skipped a major international ceremony with other world leaders in Normandy last week.

The row deepened when it later emerged Mr Sunak had conducted an ITV interview on his return from northern France last Thursday.

In a clip of that interview now released by the broadcaster, the PM has been shown apologising for his late arrival - suggesting he wanted to leave Normandy earlier.

'Very nice to see you, sorry to have kept you,' Mr Sunak said to journalist Paul Brand, adding of the D-Day 80th anniversary commemorations: 'It all just ran over.

'It was incredible but it just ran over... so apologies for keeping you.'

Mr Sunak's political opponents seized on the 'insulting' exchange to claim it showed how the PM viewed D-Day as an 'inconvenience'.