Labour frontbenchers have been left uneasy by a “spectacularly misjudged” advert claiming that Rishi Sunak does not support jailing child abusers, but party strategists are preparing to double down on the aggressive campaign. Keir Starmer faced calls to personally apologise and order the retraction of the ad, which, a campaign group warned, “poisons the water that we all must drink from”. But a shadow cabinet minister argued that it should not be pulled. Labour also released a second ad which blames the prime minister for nearly 1,000 adults avoiding prison since 2010 despite being convicted of possessing a gun with intent to harm. Senior Labour sources indicated that the party would be unapologetic in trying to tie Sunak to the last 13 years of Conservative government and four previous administrations. A wider strategy to escalate attack ads will be rolled out as planning ramps up for a general election as early as next spring, they said. However, there are concerns among senior Labour MPs that the use of such tactics is beneath the party. John McDonnell, the former shadow chancellor, called for a climbdown after the first ad was issued. It cited statistics showing that 4,500 sex offenders of children had served no prison time since 2010 and carried the tagline: “Do you think adults convicted of sexually assaulting children should go to prison? Rishi Sunak doesn’t.” “This is not the sort of politics a Labour party, confident of its own values and preparing to govern, should be engaged in,” said McDonnell. “I say to the people who have taken the decision to publish this ad, please withdraw it. We, the Labour party, are better than this.” Shadow ministers privately confessed that they felt “uncomfortable” at the move. “It’s really distasteful,” admitted one. “I wouldn’t go on the media round and defend it.” Another said: “Arguing over who likes paedophiles more is not good politics. We should be pointing out the massive cuts to policing, the judiciary, or the courts system – that’s what will show people we’re the party of law and order.” Jennifer Nadel, co-director of the Compassion in Politics campaign, said such language “poisons the water that we all must drink from”, and “drives up hate” but “drags down standards”. She added: “Keir Starmer has rightly identified that the public want to see politicians act with respect, dignity, and decency. He can start by pulling this ad from circulation and issuing an immediate apology.” The ad was defended by Lucy Powell, Labour’s shadow culture secretary, who said it was part of the “cut and thrust nature of politics” and should not be deleted. She added that the ad was obviously “a skit” based on Sunak’s “own graphics that he extensively uses”, but admitted: “It’s not to everybody’s taste.” Hours later, Labour hurried out the second ad on gun crime. It carried a stat showing that 937 adults convicted of possessing a gun with intent to harm served no prion time, and said: “Do you think an adult convicted of possessing a gun with intent to harm should go to prison? Rishi Sunak doesn’t.” The relevance of the statistics came into question because it references data stretching back to 2010 – five years before Sunak even became an MP. Starmer himself has come under political fire as it emerged that as director of public prosecutions, he had sat on the council that issues sentencing guidelines. Minutes from a meeting in 2012 show that the council “discussed the sentencing ranges for the offence of sexual assault in the light of current sentencing practice” – prompting attacks from Conservative central headquarters about Starmer’s own record. However, a Labour spokesperson said it was up to ministers to set the statutory framework for sentencing and that the sentencing council operated only in those parameters. They also pointed to new guidelines for dealing with child sexual abuse cases in the aftermath of the Rotherham grooming scandal, which were drawn up by Starmer the following year when he ran the Crown Prosecution Service. Despite the blowback over the Labour attacks, the party is set to press ahead with hammering home more criticism of the Conservatives, particularly focusing on crime in the run-up to next month’s local elections. They are viewed as a significant flashpoint for Sunak to prove to his own Tory critics that he has what it takes to close the sizeable polling deficit, and for Starmer to show that he can maintain a strong lead in the run-up to the general election. Senior Labour sources said a tougher approach to attacking the Conservatives’ record would continue. They suggested there had been a “reassessment of what we’re up against” and that Sunak’s No 10 team had sharpened up their operation. “The Tories want to present him as the change candidate, and we recognise we’ve got to redouble our efforts to attach the last 13 years to him,” said one. Another said Labour had learned from its political allies in the US and Australia not to be too scared of taking the fight to their opponents. “It’s not about nicking the Tory playbook – it’s the fact that social democrats have beaten the right by being ruthless in taking on their record where it really matters and we have learned from that.” Some also believe the outrage from some Conservatives is confected. “The Tories churn this stuff out constantly and no one bats an eyelid,” said one insider, while another added: “They don’t like it up ’em.”