Cameron is doing nothing original in aping Brown’s spending plans. This pledge was made by Portillo in 2001 and Letwin in 2004. If the electorate didn't want it then, why should they this time? Or, to borrow a Cameroon analogy, if voters didnt want ham and cheese in the last two elections why would they go for more ham and more cheese now? A new approach is required. Meanwhile Sarkozy is talking about a five-year spending freeze and almost every other developed country is adapting for the 21st century by “expenditure reform” (see this pdf primer from the ECB, of all people). Britain, once a pioneer of spending reform, has become a museum where the virtues of big state spending remains an orthodoxy. In Osborne’s defence, Brown’s current spending plan is his most modest since SR00 – it would (marginally) lower spending as ratio of GDP. But Osborne's call for a “triple lock on stability” and reducing the tax burden “over the cycle” doesn’t set the heather alight, as they say in Kirkcaldy.
The argument for copying Brown has always been to stop him saying "Tory cuts" at electon time. This strategy is based on the laughable idea that Brown fairly represents Tory policies. The last decade has shown he will say Tory cuts anyway - even if it's flatly untrue (take last PMQs). I have a high regard for Osborne, and suspect he’ll see this for himself. His pledge to mimic Brown’s ruinous plans expires with next year’s budget. Then, he’s free to do something the Conservatives in Opposition have not dared do since 1979: give the public more of their money back
P.S. ConservativeHome makes a compelling case here.