The Labour party has dramatically jumped eight points in the polls since the release of the manifesto, cutting the Tory's lead to 15 points.
The Conservatives still enjoy a hefty majority in the latest Ipsos MORI poll for the Evening Standard, remaining unchanged at 49%, but Jeremy Corbyn's party has now increased by eight to 34% from three weeks ago – the highest percentage of the current general election campaign for Labour.
The poll is the first one conducted by telephone since Labour unveiled plans to abolish tuition fees, re-nationalise the rail network and reintroduce the 50p income tax rate for those who earn more than £123,000 ($159,000) per year as part of their manifesto "for the many".
The last time Labour hit 34% in the polls was in September 2016 and it has have not been beyond that since it was at 35% in July 2016.
Elsewhere, the latest poll does not look good for the Lib Dems or Ukip, with support for Tim Farron's party plummeting to 7% from 14%. Paul Nuttall's party also fell from 4% to 2%, meaning the Green Party have now overtaken Ukip in the polls and stand in fourth place at 3%.
Gideon Skinner, head of political polling at Ipsos MORI, said: "Labour shouldn't get too carried away by the rise they see in the polls.
"The focus on their manifesto may have helped them this week, but on many fundamentals such as leadership the public still puts them a long way behind the Conservatives, and their vote is much softer, with one in six of their supporters considering voting for Theresa May's party."