Polls put Jeremy Corbyn's Labour party at the same level of support that won Tony Blair his third parliamentary majority in 2005.
Surveys showed Labour reeling in the Conservatives at the weekend, following the launches of both parties' manifestos.
YouGov had Labour on 35 per cent support — just off Mr Blair's 35.2 per cent share of the actual vote 12 years ago — while Survation had Mr Corbyn's party on 34 per cent.
Both polls showed a sharp drop in support for the Tories.
Mr Blair managed a 66-seat majority in his final term as Prime Minister while the Tories' 33.2 per cent vote share, under Michael Howard, netted them 198 seats.
"This share of the vote is the lowest ever achieved by a party winning an overall majority at a general election," an Electoral Commission analysis said.
It was a drastic reduction from Labour's 40.7 per cent share four years earlier.
It was the Liberal Democrats who benefited from Labour's falling popularity after eight years of Blair and two years after the Iraq war was launched, winning 62 seats on a 22.6 per cent vote share.
However, the most recent surveys show them struggling to reach the 10 per cent mark, suggesting they will not return anywhere near as many MPs this time around.
Survation's latest poll found Labour had halved the Tories' lead in the space of a week, from 18 points to just nine.
YouGov also showed a nine-point gap between the two main parties.
