Michael Brown: Cameron's political trap can spring both ways

So far he has dodged the hard choices over public spending and tax cuts

David Cameron is currently a man of no fixed political abode. Happiest when walking through the division lobbies with, not against, Tony Blair he has played his new consensus politics of "we're all in this together" with great skill and genius. His 100th day as Tory leader coincided with the consequences of his strategic decision to back the Education Bill, thereby saving the tattered premiership of Tony Blair. Some Tories still believe, however, that Mr Cameron has passed up the chance, rarely given to opposition leaders, to bring to an end the rule of a weakened prime minister. But Mr Cameron was right to reinforce the impression that he is as much in the driving seat as Labour MPs when it comes to deciding the date of Mr Blair's retirement. Mr Blair governs, throughout the passage of the Education Bill at least, only with the consent of the Cameron Conservatives.

There is much to be said, from the Tory perspective, for this situation to endure as long as possible. A lame-duck prime minister is a more attractive prospect for Mr Cameron than a potentially rejuvenated Labour government under Gordon Brown. The Tory leader may relish an early opportunity to get the measure of Mr Brown in Downing Street but the attractions of the continuing debilitating speculation and acres of column inches devoted to the timing of Mr Blair's handover to Mr Brown weigh in Mr Cameron's favour.

Matters could yet still come to a head when the Education Bill reaches its third reading. Mr Cameron left himself some wiggle room in his interview on Sky News yesterday by implying he would continue to support the Bill provided Mr Blair makes no further concessions.

Backing a government "when it does the right thing" is, however, also an invitation to the Government to respond in kind by testing and dividing an opposition. And a political trap can sometimes spring both ways. Mr Brown will no doubt seek opportunities of his own to tease the Tory frontbench into the Government lobbies by challenging Mr Cameron with nifty measures deliberately intended to drive a wedge between him and his Tory backbenchers. Oliver Letwin, the Tory policy guru, is already on record as saying, during the Christmas recess, that the Tories are in favour of redistribution. Expect Mr Brown to have dissected these words in time for a possible Budget measure next week that could cause apoplexy among Tory MPs if Mr Cameron is left with no option but to walk, once again, into the Government lobbies.

There are other areas of Government policy that might yet cause further cross-party confusion. These may not allow Mr Cameron the 18 months he has reserved for policy formulation before revealing his conclusions. Mr Blair's energy review suggests that nuclear power could be a live issue for Mr Cameron long before his love-in with Zac Goldsmith reaches its climax. If he still has the stomach for the fight, Mr Blair seems to be steeling himself to conclude the inevitability of nuclear power as the answer to spiralling energy prices, security of supply and C02 emissions. Labour backbench outrage at such an outcome will also force the Tories to come to a firm conclusion probably enticing them, against Mr Goldsmith's advice, into the Government division lobby.

With so much hype about Mr Cameron's "green" credentials, he is already under growing pressure to come off the fence. Road pricing and possible penalties for the predominantly Tory drivers of "Chelsea tractors" would be as much an opportunity for Labour, under either Blair or Brown, to trap Mr Cameron.

But it is the extent to which the Tories acknowledge the growing obesity of state spending, central to the Tories' future development of economic policy that will determine Mr Cameron's long-term credibility. So far he has dodged the hard choices over public expenditure and tax cuts. The promises to put economic stability ahead of tax cuts hint at reinforcing the cross-party economic consensus. But they will not provide an escape route from facing the fact that if the Tories win power, either in 2009 or four years later, it will be because Labour will have run out of money.

The most likely scenario for a Tory government to be elected will be when voters conclude, as they did in 1979, that increased expenditure on the public services cannot be afforded. Tony Blair made himself electable when he made Labour face the need to accept 1997 Tory spending plans. But the obverse will not apply to an incoming Tory government. It is only when Mr Cameron accepts that Labour's public expenditure policies are beyond consensus that we shall know that he is destined to move, one day, to a fixed political abode - in Downing Street.

mrbrown@talktalk.net