• Schools secretary Ed Balls and his Conservative and Lib Dem counterparts, Michael Gove and David Laws, have answered questions at the National Association of Head Teachers annual conference
• Plaid Cymru leader Ieuan Wyn Jones says Labour, his party's coalition partner in the Welsh assembly government, are now a "spent force"
As the latest opinion polls suggest that although the Conservative lead is holding firm or even increasing, a hung Parliament still remains possible, Mr Cameron said the Tories had now got "momentum" in the run up to polling day on 6 May.
He said that if elected, the Conservatives would have to make some "very difficult and tough decisions" on government spending.
Speaking to the BBC's Andrew Marr show, he said while future budget cuts could be "incredibly challenging", the Tories would protect frontline services and the "neediest".
Daily Express - undeclared, but supportive of the Tories
Sunday Express - Conservatives
Financial Times - undeclared, but critical of Labour
Guardian - Lib Dems
Independent - undeclared
Independent on Sunday - undeclared
Daily Mail - Officially undeclared, but highly critical of Labour
Mail on Sunday - Conservatives
Daily Mirror - Labour
Sunday Mirror - Labour
News of the World - Conservatives
Observer - Lib Dems
People - says it favours a coalition
Daily Star - undeclared
The Sun - Conservatives
Daily Telegraph - Undeclared, but supportive of the Tories
Sunday Telegraph - Conservatives
The Times - Conservatives
Sunday Times - Conservatives
Where the Conservatives differ from Labour and the Liberal Democrats is that they intend to immediately find government savings of £6bn if elected, saying it is essential to start tacking the UK's public deficit straight away.
Both the other two main parties do not propose to start putting reductions in place until the start of the next financial year in April 2011, warning that to do so this year could risk a "double dip" recession.
Mr Cameron told Andrew Marr that while a Conservative government would have to go on and find savings above this figure to trim the deficit, he did not accept that his party had only revealed 20% of their plans so far.
"I have said very clearly, it isn't possible to explain everything that needs to be done from a position of opposition," he said.
In a wide-ranging interview, Mr Cameron said he would establish a war cabinet to focus on Afghanistan and increase the number of weeks a year that Parliament sits, attacking Parliament's three-month summer break as "absurd".
He also said the Conservatives would form a government of "quiet effectiveness", which he said would be in contrast to Labour running the country as if it was "a branch of the entertainment industry".
With an acknowledgement that the Conservatives are ahead in the polls, Mr Brown added that Labour were "fighters", and "we know what we have to do in the next few days to persuade the country".
Lib Dem leader Nick Clegg: "Labour has betrayed you"
Mr Brown attacked Tory plans to raise the inheritance tax threshold to £1m, which he said would only benefit 3,000 of the Tories' "old friends".
"It is not only unjust, it is completely immoral and I will fight it every inch of the way," he said.
Lord Mandelson, meanwhile, said the Conservatives were failing to "win back" support lost at the start of the campaign and that David Cameron's impression that he was "home and dry" was misleading.
Meanwhile, Nick Clegg urged traditional Labour voters to back his party instead.
"I understand that for some people it feels like almost a betrayal not to vote Labour, but to start investing your trust in another party," he said during a trip to Burnley. "But what I say to you is: you have not betrayed Labour, Labour has betrayed you."
The Lib Dems were boosted by the endorsement of the Observer newspaper, which said Mr Clegg was the "candidate of change".
Two opinion polls published on Sunday night suggested little change over the past few days.
A YouGov poll for the Sun suggests the Conservatives are unchanged on 34%, the Lib Dems up one point on 29% and Labour unchanged on 28%.
ICM's survey for the Guardian, carried out between 30 April and 2 May, puts the Conservatives on 33%, unchanged from last week and Labour and the Lib Dems both on 28%. While Labour's rating has also not changed, the Lib Dems are down two points
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