Labour have slashed the gap in the polls to come within nine points of the Conservative Party, making it the smallest lead Prime Minister Theresa May has had over Jeremy Corbyn all year.
A YouGov survey for the Sunday Times showed that since last week, support for Labour has increased from 31 points to 35, while support for the Tories has gone down from 49 points to 44.
The poll is the first to be released since both parties released their manifestos this week.
Several reports at the weekend have shown a growing number of voters are unhappy with Prime Minister Theresa May's policies of reducing the number of pensioners protected from social care costs and introducing means testing for the winter fuel allowance.
One Conservative MP told The Sunday Times that several frontbenchers privately voiced concerns to May that the manifesto would repel voters, complaining it was too unpalatable.
The minister said May should "quickly change the subject from the manifesto – a lot of which is a kick in the teeth for voters".
He added: "We need to get off care and pensioner benefits and start talking about the calamity of Corbyn again."
The closing of the gap in the polls will cause concern within Tory HQ. It indicates that at least for now a general election landslide is not as guaranteed as initially thought.
Another Tory minister warned that minds needed to be refocused, warning that resources were being deployed poorly.
"They're getting carried away with all this talk of a landslide, sending people to places we are never going to win," he said.
"We need to make sure we get the seats we can get."
In an effort to further cash in on Labour's momentum, Corbyn on Saturday (20 May) announced a five-point pledge to pensioners, which included promises to preserve the triple lock, the winter fuel allowance and the state pension age.