The Conservatives hope to win an overall majority at the general election next May by adopting a two-pronged strategy.
They will vigorously defend their own 40 most marginal seats, and target a further 40 which they narrowly failed to take in 2010.
However, a new ITV News/ComRes poll suggests that they are currently falling short in both aims.
Polling last week in the 40 seats most marginal between Conservative and Labour (25 Conservative held; 15 Labour held) gives Labour a lead of no less than 11 percentage points - 41 to the Conservatives' 30. This compares with 37% each in those seats at the last election.
The implied swing of 5.5% to Labour since then would not only see the Conservatives fail to make any gains, but gift Labour up to 80 extra seats and an overall majority in the House of Commons of about 30.
Labour's lead comes despite the poll also showing that David Cameron is preferred to Ed Miliband as Prime Minister by these marginal seat voters, with a majority of them saying that Miliband 'puts me off voting Labour'.
The Conservatives will hope to benefit from any collapse in Lib Dem support in constituencies where those two parties are in competition, but even gaining the 20 Lib Dem seats vulnerable to a 5% swing will only mitigate the losses to Labour predicated by this poll.
The ComRes poll is also ominous for the Conservatives in putting Ukip as high as 17% (with up to a third of electors saying they would 'consider' voting for Farage's party) in seats where the electoral arithmetic means that the battle should be focused on the major government and opposition parties alone.
And the fact that Conservative support has fallen by more than Labour's has risen clearly shows how Ukip can damage the Conservatives in these pivotal marginals.