First week by week, and now day by day, the prime minister is stepping up the way he describes the political battle between Labour and Reform UK.

Sir Keir Starmer tells The Guardian this weekend: “History will not forgive us if we do not use every ounce of our energy to fight Reform. There is an enemy. There is a project which is detrimental to our country. It actually goes against the grain of our history. It’s right there in plain sight in front of us. We have to win this battle.”

Expect more in the coming days at the Labour Party Conference in Liverpool, including in the prime minister’s speech on Tuesday.

He heads to the north west of England after a day in the company of fellow left-wing leaders at a conference in London.

I was standing at the back of Methodist Central Hall in Westminster listening to a quartet of prime ministers. Sir Keir was joined by his opposite numbers from Canada, Australia and Iceland.

And here’s the thing: while they are all winners, they had the demeanour of those with pensive worry.

The rise of Reform here in the UK is far from unique.

There was a confessional vibe at times to the conversation, borne of a fear the left can exude a piety and loftiness off-putting to many.

Sir Keir’s take on this was that Labour took far too long to recognise the deep-seated concerns from many about illegal immigration.

It was an observation some within Labour are weary of hearing about again, recalling the fuss a decade ago when Labour had mugs printed with the promise of “controls on immigration”.

Others say Labour cannot highlight its instinct to be tough too much, given the instinct of many, fairly or otherwise, is to assume they might be the opposite.

Amid the noise of this debate comes the plan for digital ID.

After two decades of rapid digitalisation, from the smartphone’s invention to its near ubiquity, the prime minister reckons the centre of gravity around the whole issue of state-mandated ID – and our collective willingness to embrace it – has shifted.

Twenty years ago, Tony Blair was making the case for ID cards. The ‘card’ bit of the idea feels rather vintage, but the ID bit is back as an idea.

It is an idea still lacking in key detail, but one Sir Keir wants to enthusiastically embrace.

He told me a few weeks ago as he began to publicly toy with it that plenty of us are now much more used to handing bits of personal data to all sorts of institutions and companies we deal with online.

So, the logic goes, plenty will be comfortable doing the same thing with the government.

Let’s see.

What is undoubtedly the case is that there is, again, noisy opposition to the idea.

A petition on Parliament’s website has reached well over a million signatures. Only a handful have cleared that threshold in the last decade.

The prime minister will hope a quieter majority are won over by the idea – and he already has his political dividing line with Reform. And with the Conservatives, Liberal Democrats and Scottish National Party, as it happens.

His challenge, against the toughest of backdrops – economic, political and international – is to prove he can deliver incremental, or better, improvements for voters, and convince enough that the embrace of Reform would be a big mistake.

Sir Keir is now unflinching and explicit, talking of what he calls the “open fight” he wants with Reform – a “battle for the soul of this country”.

On that characterisation of the tussle ahead, at least, Reform agree that is precisely what it amounts to.