The Tory party has recorded its lowest approval rating in a mainstream opinion poll since November, with Ukip pulling in more than double the points of fourth place Greens.
According to a TNS poll, 33% of the UK would vote for Labour in the upcoming general election, compared to 27% who would pick the Conservatives.
Ukip came in third with 18% of the vote, followed by Greens (8%) and the Lib Dems (6%).
The poll is in contrast to recent studies which have frequently put the Tories and Labour party neck-and-neck. A recent YouGov survey put both parties at 31%, with a previous YouGov survey tying them both at 32%.
A study for the Sun also placed the Tories in the lead with 34%, followed by Labour on 33%.
Elsewhere, the study revealed more voters would like to see Conservatives or Labour go into coalition with Ukip, rather than with the Lib Dems, if the 7 May general election ends in a hung Parliament.
Around 29% said Conservatives should go into coalition with Ukip, against 25% who said they should continue with the Lib Dems. More voters (26%) also thought Labour should form a partnership with Ukip than with Lib Dems (23%).
The study also said 57% of voters thought the growth of smaller parties, such as Ukip and the Greens, was good for British politics, with 43% believing they would become a permanent fixture on the UK political landscape.
TNS director Jamie Willard said: "This latest TNS poll shows we are witnessing the edge of politics joining the mainstream; with 57% of those surveyed saying the growth of minority parties is a good thing.
"Indeed, with Ukip now seen as the favoured coalition partner for both Labour and the Conservatives, it suggests that Ukip are drawing support from across the political spectrum.
"Interestingly though there seems to be a mismatch between the public's expectations on the likely number of seats the minority parties will go on to win, and current forecasts.
"It is also striking that almost half of those planning to vote for a minority party are doing so out of dissatisfaction with the main three parties. We truly are seeing a Britain in flux."