Sir Keir Starmer has heaped pressure on Sadiq Khan to scrap his ultra low emission zone (Ulez) expansion after the policy was blamed for losing the Uxbridge and South Ruislip by-election.
The Opposition leader warned his party must “learn the lesson” of the defeat as he called on the London Mayor to "reflect" on his plans to apply a charge for the most polluting vehicles to all boroughs of the captial.
Both Labour and the Tories are coming under pressure to reconsider their green policies in the wake of the Uxbridge result.
While Labour considers the impact Ulez may have at the next election, Tory MPs have pointed to the unexpected by-election win as proof that Rishi Sunak should scale back on the Government's net zero plans.
Conservative candidate Steve Tuckwell warned Labour that Ulez was to blame for them losing in Uxbridge and South Ruislip
Speaking at his party's national policy forum in Nottingham this morning, Starmer said there was “something very wrong” when a party policy was on “each and every Tory leaflet”.
He said: “That result in Uxbridge demonstrates there is never any reason to be complacent and never a reason to rest on our laurels.
“It is a reminder that in an election, policy matters.
“We are doing something very wrong if policies put forward by the Labour Party end up on each and every Tory leaflet.
“We’ve got to face up to that and to learn the lesson.”
Despite the warnings from his party leader, Khan has insisted he will plough ahead with the Ulez expansion.
Sadiq Khan' has vowed to plough ahead with Ulez
Pending the outcome of a court challenge, from next month the Mayor will widen the £12.50 daily charge for cars which fail to meet emissions standards to beyond the capital’s north and south circular roads.
Speaking to GB News, the deputy chairman of the Conservative Party and MP for Ashfield, Lee Anderson said that the Tories had only won in Uxbridge because they campaigned against the Ulez expansion on the doorsteps.
He said the unexpected victory in Uxbridge and South Ruislip had "given us a flicker of hope" but the party needed to "learn" from the Ulez campaign.
He said: "There's a certain course that we're that we're travelling on and it's been not good for the other two by elections. But the one that we did win, it's given us a flicker of hope, in that there was one thing that was actually campaigned on - this terrible tax, this tax on fresh air, this is this money grab from Khan.
Rishi Sunak is also facing pressure to reconsider his green policies
Lee Anderson told GB News the Conservatives must 'learn' from the Ulez campaign
"I think we have to learn lessons from this. We all know that by elections, especially when you're coming to the end of the Parliament, will be very difficult for the incumbent government. We were punished."
Anderson, who has previously said that voters are 'sick to death' of net zero added "Let's not be arrogant but realise that our voters out there do want to vote for us.
"Nobody disagrees with the notion that we've got to make our planet much cleaner and leave this planet in a better condition than when we arrived. The one thing that concerns me about Net Zero is the fact that we seem to be doing it quicker and faster and more costly than any other nation.
"I worry about the constituents in Ashfield when they're struggling to pay their gas bills, and electric bills and struggling to fill the car up at the petrol station.
"So I would say what we need to do is have a rethink, because if we don't look at Uxbridge and the reasons for the win - the candidate Steve (Tuckwell), was quite clear: he didn't take any credit for the win and he didn't give any credit to the party, it was all down to the Ulez campaign.
"It was Labour who lost that campaign, and thank goodness, because it's given us a little bit of hope and I just hope that some of us aren't too arrogant to look at the results and think we can just plough ahead."