The new ComRes poll showing support for the Conservatives falling again is likely to have led to some anxiety at CCHQ this morning. Seven out of the last ten polls have put the Tories below the psychologically crucial figure of 40 per cent. Today's poll is the third in just over a week to show figures that, if repeated at the election, would produce a hung parliament.

The Tories will comfort themselves with the weekend YouGov poll that gave them a 6 point lead over Labour in 32 key northern marginals. The fear remains that the millions Lord Ashcroft has pumped into marginal seats will ensure that in practice David Cameron wins a working majority.

Despite this, the decline in Tory support is still explicit enough to encourage those who have long argued that Cameron should adopt a more populist, right-wing agenda. Over at PoliticalBetting, Mike Smithson notes that the Tories have started to lose support to Ukip in the wake of Cameron's decision to abandon a referendum on the Lisbon Treaty.

ConservativeHome's Tim Montgomerie suggests that the fall in support has less to do with the party's new position on Europe and more to do with the breach of trust that Cameron's decision to abandon his "cast-iron guarantee" of a referendum represents.

I'd add that the Sun's vulgar campaign against Gordon Brown damaged the Tories by association and that rising confidence means the economy isn't quite the political headache it was for Labour.

The biggest danger for the Tory leadership is that the party's persistent decline in support will undermine its policy agenda. George Osborne's "age of austerity" was predicated on the assumption that the Tories would win a large majority at the next election, providing them with the parliamentary support necessary to push through unpopular spending cuts and tax rises.

This is a major test of Cameron and Osborne's resilience.

Follow the New Statesman team on Twitter