James Johnson is co-founder of the pollster JL Partners, and formerly ran polling for Downing Street.

I spent most of last year telling disappointed journalists that the public still like Boris Johnson.

Whether it were Covid lockdowns, Owen Paterson, tax rises, fuel shortages, government contracts, or Downing Street wallpaper, I would get an excited call asking if the game was finally up for Johnson with the public.

Each time, my message was the same.

Though there might be ups and downs, the polling and the focus groups were fundamentally unchanged. People who voted Conservative before were still going to vote Conservative, and Johnson was still getting the benefit of the doubt in what people saw as a tricky situation under the pressure of a pandemic.

Now, everything has changed. In mid-January, as Partygate reached its peak, the public’s patience snapped.

Not so much because of the parties themselves, but because of what they saw and still see as repeated lying and cover-up by the Prime Minister and those around him.

They felt taken for fools, lied to, and mocked by a politician they had liked. They were no longer laughing with the Prime Minister: he was laughing at them.

I wrote up these responses at the time, from focus groups in Cheltenham and Bolton North East. They show the damage done to Johnson, not just on trust but on his strength and competence too.

The Prime Minister was described – by Conservative voters – as “a coward”. He was someone who “was a bit different to the David Cameron, Eton-education typical Tory” but had now “completely lost everyone’s trust”. The once strongman who got Brexit done was now someone who “lacks gravitas” and “has got to go”.

Despite the war in Ukraine, that fury did not fade. While some commentators were heralding a polling boost to Johnson in February and March, the message from the focus groups remained bleak.

It is not just trust that is lost in Johnson. The line from a recent focus group that stands out most for me is from a first-time Conservative voter. He despaired that “Margaret Thatcher would never have had those parties. She was strong and would have told them to stop”.

Labour remains a stretch for him, but he said he would not vote for the Tories while Johnson remains leader.

This is what is so damaging about Johnson’s position. His best assets in 2019 have now become his weaknesses.

Voters in the Red Wall liked him because he was strong, because he could get things done, and even if it might upset a few people he would ultimately deliver. That view is now fatally undermined. Now Starmer leads Johnson on “knows how to get things done” and “strong”.

Even if Partygate goes away or people tire of it, the brand damage will not. If it did not improve over the last three months, with a war in which Britain led the world and Johnson backed by his MPs for most of the period, why should it recover with more fines, the Gray report, and a parliamentary inquiry to come?

The situation is serious: Labour have now closed the gap on the economy, Starmer has an eight-point lead over Johnson on who would be the best Prime Minister in a way that Miliband and Corbyn never did, and Labour are ahead on voting intention.

There is an additional paradoxical danger: there is a possibility the local elections go better for the Tories than expected.

This should not be taken as a vindication of Johnson. Change will be on 2018, not December 2019, and many places are not voting. Add in the fact that local Conservatives have a strong message on council tax in London, and the results could obscure just how bad the picture is for the Tories nationally.

Come 2024, the Party does not need to lose by a Major-style landslide to forfeit power: they can lose their majority while being ahead on votes. Under their current leader, they risk sleepwalking to electoral defeat.

There is one silver lining to all of this for Conservatives. Voters’ scathing commentary, at the moment, is reserved for the Prime Minister rather than the wider party. Without Johnson, it is possible to see a significant transformation to the Party’s electoral fortunes, especially with Labour still floundering to seal the deal with voters.

Our system may be parliamentary, but the way voters view the parties is presidential. How a party is seen on a range of issues – for example on economy, crime, or housing – depends on how much people think the leader of the party can be trusted and can deliver.

A commonly used polling question is one that asks people to say whether they trust Labour or the Conservatives more on a given issue. A recent YouGov poll found the Conservatives behind Labour on every issue apart from defence and terrorism.

But ask the same question in a focus group – face to face with voters – and with the exception of the economy, you get blank faces in response.

People literally cannot answer, because they do not know the ins and outs of Conservative or Labour positions on each policy area. They just know whether they feel they can or cannot trust that party and their leader to deliver.

As the YouGov poll shows, currently this phenomenon is disadvantaging the Conservatives.

Take the Rwanda plan on immigration: though popular with the voters Johnson needs, it fails to resonate with voters because it is Johnson’s policy. As one voter in a recent focus group in Crawley put it to me, how can we know it will even happen?

But this can equally mean that with a new leader, the Tories can swing back on many of these issues. There is no deep-seated hostility to the Conservative Party as a whole amongst voters – certainly nothing like there was in the 1990s. The Conservative brand is not tainted beyond repair.

What of the contenders? The Prime Minister’s defenders say that the party cannot make a change, as there is a lack of viable choices available.

But recent YouGov polling found that every prominent Cabinet minister – with the exception of Priti Patel – has a higher approval rating than Johnson.

Conservative members, often touted as the most loyal to Johnson, agree. This website’s own Cabinet rankings table show many Cabinet ministers are ahead of Johnson, with Liz Truss, Ben Wallace and Nadhim Zahawi scoring best. That is before getting onto talent outside of the Cabinet, like Penny Mourdant or Tom Tugendhat.

I am a pollster. I report – without any sugar-coating – what the British public think. But I am also a Conservative. I want the party to succeed. It is now at risk of failure.

The Tory brand has the potential to be reborn. But it is now, in a way it was not before this January, smothered by its leader who is seen by the public as a rule-breaker and a liar who can no longer deliver.

Number Ten say that Conservatives must rally around the Prime Minister. But every time MPs do, the more the yoke of his toxicity risks strangling the Party’s wider electability. Already I have noticed focus group attendees singling out ministers for defending Johnson on the airwaves.

Number Ten say there are no other choices. But come a leadership contest different views and visions would fizz to the surface, giving MPs a clear choice ahead of the next general election – and a new leader would give the Party a fresh hearing with the country.

Number Ten say removing Johnson would guarantee electoral defeat. But everything about public opinion suggests the opposite is true. It is doing what Downing Street says – keeping the Prime Minister – that is the gamble, not removing him.

Will Conservative MPs take the one-way road, fraught with danger, by sticking with Johnson? Or will they salvage the Conservative brand while they still can?