With impressive speed David Cameron and Nick Clegg learn the awkward choreography of coalition politics. Their command is instinctive, since neither leader has any previous experience of government let alone of sharing power. Both seem to know the moves that are required to keep the show going, like two young dancers cast together for the first time in a performance for which they had never rehearsed.

In the build-up to last week's elections, the two leaders pirouetted separately around the stage and now they come together as if separation and union were seamless. Yesterday, both wrote separate articles with a similar message, insisting they would not move left, nor right in the wake of what happened. In the coming days, they will deliver variations on the same theme, together and apart.

The problem for both of them is that the substance of the message matters more than the co-ordinated method of delivery. The message is unconvincing. In yesterday's Daily Telegraph, Cameron wrote: "I get the message, loud and clear. I know that the familiar excuses – low turnout, mid-term blues – aren't enough.... I get it."

I sensed his opening message and indeed the rest of the article had a familiar air. On Twitter, the political journalist Gaby Hinsliff reminded me why. She pointed it out the "I get it" act of contrition was the exact phrase Tony Blair used in 2000 after the row over the 75p pension rise. The rest of Cameron's article deployed another familiar Blairite trick: he argued that he was not moving left nor right, implying he was on the centre ground. Blair used to insist that the left and right might be opposed to him but he would march on.

Electorally successful leaders have always had their own distinct, authentic voices. They can be awkward, rough voices. But listen to Wilson, Thatcher or Blair and they were all original, none of them copying the style or language of those that had flourished before them. Almost inevitably, the original is more effective than the imitator. Blair told his party conference in 2000 that he "got it" over a specific policy, a puny pensions' rise that was easily addressed. Cameron revised the same phrase in a way that was far more imprecise, suggesting that what he got was a desire from voters for him to focus on "what matters". This is not so easy to address.

Everyone agrees that the economy and public services "matter". The policy direction is what is causing concern, with a double-dip recession and, among other rushed-through reforms, an overhaul of the NHS. This is the broader reason why the old Blair devices will not work for Cameron. He leads a government of the radical right, even if his leadership is not right-wing enough for an element of his party, whereas Blair clung to the centre ground as if his life depended on it. I am not arguing that Blair's approach was the correct one, but I am suggesting that an act of imitation will not get Cameron very far in a very different context.

Nick Clegg's response to the local elections in a separate article was slightly more precise in terms of his policy agenda, but had at its core a flaky premise. Clegg writes: "The first two years of the Coalition were a rescue mission for the economy. The second half has to be about reform." If the economy had been rescued, voters would no doubt raise a cheer. But the economy was growing at the time of the election and is in recession now. It needs a rescue mission from the rescue mission.

Internally and beyond, there is an understandable focus on what the two ruling parties disagree over, but the biggest challenge arises over what they agree on. Nearly all of the spending cuts in the first, rushed spending review are still to be implemented and then there is another round to come. It is much easier to be in favour of spending cuts in theory than when faced by specifics. I note that some ministers warn already that the first review is testing their departments to the limit.

The Liberal Democrats played an important role in that review. Without them, the BBC's budget would have been slashed to a point where even that generously managed institution would have struggled. There would have been no limit to tuition fees, and housing benefits would have been cut further. But in theory they have signed up to another bloody spending round, this time with some evidence to suggest that their rush towards austerity has made matters worse.

In making his case, Clegg also deploys the Blair formula, arguing that the Coalition will lurch neither to the left nor right. Clegg's allies tell me that their pitch at the next election will be that it is the Liberal Democrats alone who are now the party of economic competence and social justice. The combination was the other part of the Blair formula for winning elections, but one that depended on their being a tangible level of economic competence and social justice.

Both Cameron and Clegg manage the exhausting dynamics of coalition politics with the sensitivity of the best political artists. Their joint message as they embark on an act of political renewal this week lacks artistry and is challenged by what is actually happening rather than what they hoped would happen.

s.richards@independent.co.uk