The first rule of political attack is that whatever you say about your opponent reveals more about you than about them. In that regard, the Tories’ campaign appears dodgy and duplicitous, but determined.

After the 2017 election, James Johnson, one of Theresa May’s advisers, delivered a postmortem to the cabinet that showed they had barely landed a punch on Jeremy Corbyn, and their campaign had only served to make voters feel they could vote Labour with impunity.

The Tories’ campaign this year is clearly a reaction to what went wrong in 2017. So there was no question of Boris Johnson ducking the debates (something that cost May support), there has been very little fresh policy (the Conservatives are learning the lesson of the social care announcement) and there is no complacency about the threat of Corbyn.

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The Tories are fighting Labour as if they were neck and neck, and when fights are close they get more vicious. We have not seen a Tory campaign so heavily skewed towards attack since 1992. The only proposition they have is to “get Brexit done”. Everything else is focused on reminding voters that Corbyn is a real risk and terrible threat.

A pattern is emerging in the type of attacks the Conservatives are willing to make. Their economic dossier exaggerated Labour’s spending plans to a degree that no independent judge could take seriously. They fabricated the ending to a video of Keir Starmer in order to highlight Labour’s indecision. During the leaders’ debate, they changed the name of the Conservative press office’s Twitter account to “factcheckUK” in an attempt to impersonate an independent fact checking account that clearly risked misleading voters.

Each of these moments show that the Tories are willing to do whatever is required to make sure their message about the dangers of Corbyn as prime minister stays in the news and trends across social media.

I have not seen tricks as dirty as this since the Labour campaign that I was part of in 2005. Early in that campaign we recorded and released a secret tape of Howard Flight, then a shadow cabinet minister, suggesting the Tories would make deep cuts to public services. He was sacked. From then on, Labour were repeatedly accused of dirty tricks, but the Tories were on the back foot.

Liam Fox, then Tory party chairman, spent a week accusing Labour of outrageous “black arts” but every time he took to the airwaves in denouncement represented us knocking them off their message.

It was a morale boost every time Labour HQ heard him complain. Meanwhile, all the public could hear above the noise of an election was something about Tory cuts, even from the Tories themselves.

There is a lesson here for Labour’s strategy team. Every minute given to stories about the Labour spending dossier, the stitched-up video and the duplicity of their tweets is time spent on topics the Tories want to talk about, instead of Labour’s messages. There is a surfeit of information in our lives: what we all suffer from is a poverty of attention. Voters just don’t have time to pick through the bones to get to the truth.

Perhaps the manifesto launch will allow Labour to set out a positive vision that catches public attention, just as it did in 2017, but the difference this time is the Tories are waging an effective war of attrition. They don’t need to land punches on Corbyn to be successful, they just need to make it harder for Labour’s positive message to reach voters. If Labour voters in the north, the Midlands and Wales hear only rows about Brexit and process, they won’t heed the call to come back.

In the next three weeks, we should expect more outrageous and misleading attacks that distract voters from Labour’s positive message. If Johnson wins with a majority on 12 December, then, regardless of the dirty tricks, the Tory campaign will be lauded, just as ours was in 2005.

So what should Labour do? They must give the manifesto a chance to break through, but also go on the attack. In 2016, Michelle Obama memorably told the Democratic National Convention that “when they go low, we go high” and while that might have worked for an Obama, the Democrats lost to a campaign that went very low and which ultimately won by suppressing motivation to turnout among Democrats.

Labour needs to remind those who voted Labour in 2017 why they voted against the Tories, and they need to do so with more bite. Fight fire with fire: pin Johnson back on to areas that he does not want to talk about, so that it is harder for him to make this election all about Brexit. The Tories have learned the lessons from the 2017 campaign and now this is a different fight: they are successfully stopping Corbyn’s positive message from gaining the traction it did last time.

When Labour makes its manifesto announcement, expect another low blow from the Tory attack machine. Labour strategists need to adapt quickly: in politics, there are no prizes for playing nice.

• Theo Bertram is a former adviser to Tony Blair and Gordon Brown