More than half of Scots plan to back the SNP in the general election, shattering Ed Miliband's hopes of securing a Labour majority. SNP leader Nicola Sturgeon has been buoyed by a series of TV debates opposing austerity cuts, despite threatening another referendum on independence. A new TNS survey shows the SNP has almost doubled its lead over Labour in a month, with 52 per cent now backing Ms Sturgeon with only 24 per cent of Scots planning to vote for Mr Miliband. Scroll down for video . A new TNS survey shows the SNP has almost doubled its lead over Labour in a month, with 52 per cent now backing Ms Sturgeon with only 24 per cent of Scots planning to vote for Mr Miliband . The 28-point lead is nearly double last month's figure, when the parties scored 46 per cent and 30 per cent respectively. The Conservatives scored 13 per cent (down one percentage point), the Liberal Democrats 6 per cent (up three points) and the Greens 3 per cent (down one point). Support for Ukip in Scotland is 'almost negligible', TNS said. The SNP surge since the independence referendum in September puts Labour on course to lose dozens of seats, robbing Mr Miliband of any chance of winning the election outright. It comes on the day that Mr Miliband used Labour's manifesto launch to insist he is 'ready' to be Prime Minister. Ms Sturgeon has offered to work with Labour to lock the Tories out of power, even if David Cameron wins more seats on May 7. The poll is a blow to Mr Miliband on the day he used Labour's manifesto launch to insist he is 'ready' to be Prime Minister . But Labour and the SNP have clashed on Ms Sturgeon's call for full fiscal autonomy for Scotland, and her suggestion that another referendum could be held before 2020. The TNS survey covered the period of the UK-wide TV debates, although it closed before the impact of the Scottish leaders' TV debates could be taken into account. Tom Costley, head of TNS Scotland, said: 'The official election campaign has got off to a great start for the SNP, undoubtedly helped by Nicola Sturgeon's strong performance in the UK-wide TV debate. Not only has Labour's hopes of a recovery in support been dashed but, even worse, it appears to have gone backwards. 'The SNP seems to be building on the momentum which they carried forward from the independence referendum, while Jim Murphy is still struggling to win back Labour's lost supporters. Indeed, the latest poll shows some evidence that the growth in SNP support is mainly coming from disaffected Labour supporters. 'But it's important to remember that the campaign is really only beginning and 29 per cent of those who say they are certain to vote have not made up their minds who to vote for. It will be interesting to see what difference the campaigns of the various parties make to people's intentions by polling day.' Support for the SNP continues to be very strong among younger voters who are certain to vote and express a preference - 71 per cent of 18 to 34-year-olds, against 57 per cent for 35 to 54-year-olds and 40 per cent for those aged . 55 and over. Among the oldest age group, Labour scores 32 per cent and the Conservatives 20 per cent. However, fewer of the younger voters say they are certain to vote - 52 per cent of 18 to 34-year-olds against 67 per cent overall. In the event of a hung parliament, 44 per cent of Scottish voters would prefer a Labour-led government compared with 15 per cent who back a Tory-led administration. SNP leader Nicola Sturgeon has been buoyed by a series of TV debates opposing austerity cuts, despite threatening another referendum on independence . The most popular single option is a Labour-SNP coalition, with 25 per cent support. Both parties have ruled this out, but the response suggests that some form of SNP-Labour co-operation has significant backing, TNS said. The next most popular option is 9 per cent for the continuation of a Conservative-Liberal Democrat coalition. Nearly a third (31 per cent) of Labour voters would prefer the option of co-operating with the SNP, while 28 per cent opted for a Labour minority government. If the SNP holds a majority of Scotland's 59 seats in a hung parliament, voters are evenly divided between those who want the SNP to work with Labour (34 per cent) and those who want the SNP to remain a separate bloc in the Westminster Parliament (32 per cent). SNP voters are also evenly divided - 42 per cent want to work with Labour and 45 per cent would want the party to remain separate. Ms Sturgeon yesterday  left the door open to a second referendum on Scottish independence before 2020. Before last year's historic vote, Scottish nationalists insisted it was a once-in-a-generation chance to decided on the future of the 300-year-old Union. But Ms Sturgeon has refused to rule out demanding a re-run within the next five years, prompting opponents to claim she had 'broken a promise the size of Ben Nevis'.
52% of Scots backing the SNP, doubling lead over Labour trailing on 24% .
Sturgeon buoyed by TV debates despite threat of another referendum .
Damning survey comes on the day Miliband launches Labour manifesto .
TNS surveyed 978 adults aged over 18 across Scotland between March 18 and April 8 .