Conservatives have urged Mr Cameron to be more right wing and ignore “wishy washy” Lib Dem demands for gay marriage and reforming the House of Lords.
There have been renewed reports that that senior Liberal Democrats believe the party needs to withdraw from the Coalition if it is to avoid devastating electoral losses in 2015.
The rumours followed the observation from the Lib Dem deputy leader, Simon Hughes, yesterday that some Conservatives thought they were “born to rule”.
Mr Cameron said he believed that the Coalition government “is delivering” but accepted that the country faces “a difficult time”.
He defended the austerity measures as vital to cutting the deficit, and insisted that the Coalition is “as important today as it was two years ago”.
“We have to be very frank with people that it is tough, it is difficult, but these are the right steps to take,” he said.
Mr Clegg said the Coalition should be judged by its actions, insisting he cared “more about children from disadvantaged backgrounds doing well” than “House of Lords reform”.
But he added: “A smidgeon of democracy, I don’t think will go amiss, since we have been talking about it for about a hundred years.”