The Lib Dems would be Labour on Steroids.
Clegg boasts that he is an Obama wannabe. After 18 months most Americans now see that Obama is an empty suit dishonest thug fraud shoveling money and power to corrupt cronies. His appeal was based on fear hate ignorance and manipulation by arrogant and discredited elites in a campaign using vast amounts of foreign money.
If Cameron wants to break from the pack he should hammer Clegg on this connection. The Lib Dems should be labeled as the Obama Party. They should also be labeled explicitly as the Global Warming Fraud Party. These two associations should be tied to Clegg like 20 pound weights, one to each leg.
If the Tories do this and focus the attack on these two issues on Clegg then the Lib Dem bubble will pop. Labour would not benefit from this since the first issue will remind the British public of Blair and the second will remind them of the Quango and Euro-centric governing principles of both Labour and the Lib Dems.
The beneficiaries of a final campaign push based on my plan would be the Conservatives and the UKIP. Between now and the election the UKIP should I think hammer the BNP as ignorant racist socialists whose authoritarian influence would prove a Trojan horse for Islamism, bankruptcy and the ultimate loss of sovereignty to Brussels or Russia or the Ummah.