PM stands by campaigning tactics
David Cameron has signalled he will resist pressure to rethink his General Election tactics, after Ed Miliband said the hallmark of the Conservative campaign had been "desperation".
Mr Miliband accused the Tories of sinking into personal abuse and said that a failure to make a breakthrough in the polls had panicked Mr Cameron's party into making "unfunded and unbelievable" spending promises.
But Mr Cameron insisted the Conservatives were making a "very strong argument" and said he would continue to frame the May 7 General Election as a choice between himself and Mr Miliband as prime minister.
Labour was buoyed by three opinion polls giving them a national lead of between three and six points after weeks in which Tories appeared to be very slowly edging into a lead.
And Defence Secretary Michael Fallon's claim that Mr Miliband was ready to "stab the United Kingdom in the back" over nuclear weapons was poorly-received even by traditionally Tory-backing newspapers like the Daily Telegraph, which branded it "ill-judged".
But other surveys continued to give Conservatives a slim one-point lead, while in Scotland Mr Miliband's party seemed to be making little headway, with a YouGov poll for The Times putting the Scottish National Party on 49% against Labour's 25% - a tally which could see their representation reduced to just four Scottish MPs.
Making his first campaign foray north of the border in a bid to stem the SNP threat, the Labour leader kept his sights trained on the Conservatives, as Mr Cameron announced plans for a real-terms freeze on train fares and three paid days off for workers who want to volunteer.
"Desperation is becoming the hallmark of David Cameron and this Tory campaign," said Mr Miliband.
"This week we have seen them defending the non-doms and descending to personal abuse. Today, in further signs of panic, they are announcing billions of pounds of unfunded and unbelievable promises.
"They can't explain where the money is coming from. They can't tell us how they will make these promises happen. They simply won't be believed. And the result if they were returned to government would be even greater spending cuts, putting the NHS at risk, with inevitable rises in VAT."
Speaking to reporters during a visit to Devon, Mr Cameron insisted he would not change his approach to the campaign.
"I am talking about this every day, which is there is a choice of leaders and there is a choice of teams to run this country," he said. "I will be talking about that the day before polling day as I am today."
Asked if he liked Mr Miliband personally, the PM said: "I don't really know him, to be honest ... but we have a profound disagreement about how to run the country. In the end, whether you call it personal or not, elections are about choosing the team to take the country forward."
The PM denied the Tories had suffered a "sticky" week of campaigning. "I wouldn't say that is what has happened at all," he said. "I would say you have seen a very strong argument coming from the Conservative Party ... I think that argument is only getting stronger."
And he repeated his warning of the dangers of minority Labour administration propped up by nationalists in a hung Parliament, claiming that Mr Miliband's party seemed to be "in alliance almost with the SNP".
Speaking alongside Scottish Labour leader Jim Murphy and shadow chancellor Ed Balls in Edinburgh, Mr Miliband launched Labour's strongest attack yet on the SNP, claiming its plans for full fiscal autonomy for Scotland would create a £7.6 billion funding gap which would be "a devastating blow to working people".
Mr Miliband said he would never "sell Scotland short" by ending arrangements under which public tax and spending needs are pooled by the four nations of the United Kingdom.
But SNP leader Nicola Sturgeon dismissed the broadside as "desperate", insisting that the only cuts people are facing are "the ones that the Tories are proposing and Labour are backing".
And Mr Fallon said Mr Miliband's visit to the Scottish capital showed that "the SNP are already pulling Labour's strings".
"If it's like this now, imagine what it would be like with the SNP propping up Ed Miliband in Downing Street," said the Defence Secretary. "Borrowing, taxes, our defence policy - all of it would have to be signed off by the SNP.
Unveiling his rail fare policy, Mr Cameron said extending the existing RPI inflation cap on regulated ticket prices for another five years would save the average commuter £400.
"It shouldn't just be taken for granted that people across the country who get up early and come home late, spend a large amount of the money they earn travelling to and from work," he said.
And the Prime Minister said that the proposal for three paid days a year for volunteering would be "good for our economy, as it will help create a better, more motivated workforce. And it's good for our society too, as it will strengthen communities and the bonds between us".
The Campaign for Better Transport hailed Tory plans for a real-terms freeze in rail fares as "definitely a step in the right direction" after a decade of inflation-busting rises.
But train drivers' union Aslef said Mr Cameron's promise would guarantee rises in line with inflation, which would "hit the poorest the hardest", while RMT leader Mick Cash said it would "institutionalise the harsh reality that the British passenger pays the highest fares in Europe to travel on rammed out and unreliable trains".
Elsewhere on the campaign trail, Labour pledged to protect the jobs of 10,000 beat bobbies as it launched its policing manifesto.
And Liberal Democrat leader Nick Clegg, who is spending the day in his Sheffield constituency, said his party would allow working 18 to 30-year-olds to claim a low-interest government loan of up to £2,000 to move out and rent their own home.
He said it would help the "clipped wing generation" who are unable to leave home and the parents "who want their kids out of their hair".
Asked by Channel Four News' Michael Crick whether he and his party looked like "arrogant public school bullies", Mr Cameron said: "For heaven's sake Michael ... I haven't met anyone who takes that view."
He added: "Frankly, the point about Ed Miliband - really to say he stabbed his brother in the back is hardly adding to the political lexicon of Britain. It is a point that has been made by almost everybody else including many people in the Labour Party."
Pressed on whether he regarded Mr Miliband as a "decent man", the PM replied: "I don't really know Ed Miliband that well. All I would say is that his political ideas are the wrong ideas. All the things we did to get the country back on track ... every single dot and comma he opposed."
Mr Cameron went on: "This isn't an election about whether he is decent chap or not. The question is who has got the right team and the right ideas to take the country forward?"