Jim Murphy: SNP are David Cameron's 'little helpers'

Labour's Jim Murphy has called the SNP David Cameron's "little helpers".

The party's Scotland leader said the PM "needs someone else to win seats for him in Scotland - beat Labour for him".

Mr Murphy said if current polls were repeated on election day, Labour and the SNP would end up working together - in opposition to the Conservatives.

The Conservatives say Labour are trying to get into power on the SNP's coat tails. The SNP say only they can ensure Scottish influence over Westminster.

The Lib Dems' Scottish leader, Willie Rennie, told BBC Radio Scotland's Good Morning Scotland programme the UK needs Liberal Democrats in government to prevent the bigger parties "veering off to the left and right".

The leaders of the major parties in Scotland were speaking out as an opinion poll released on Tuesday cut the SNP's lead over Labour in a large number of seats.

Policy guide: Where the parties stand

'We're the underdogs'

Mr Murphy accused the SNP of "playing the role of David Cameron's little helpers" because the Conservative leader "knows he can't win in Scotland".

Using a football analogy, he told BBC Radio 4's Today programme: "In Scotland we are behind in the opinion polls - yes, we're the underdogs - but the first ball's just been kicked in this campaign.

"We're nowhere near half time, let alone the final whistle - we can turn this round. There are polls today that show that in 40 seats in Scotland, we're not 17% behind, we're 6% behind. We're within striking distance.

"We've got a lot of work to do and we even know that improved poll this morning - if it was repeated on election day - we'd lose a lot of seats. The SNP would be really pleased, but David Cameron would be absolutely delighted."

The Conservatives' leader in Scotland, Ruth Davidson said it was "absolutely possible" the SNP could end up with a majority of Scottish seats.

'Progressive change'

She told BBC Radio 4's Today she would prefer not to enter into any coalition deals if the Conservatives fail to win a majority, preferring a minority Conservative government, she said.

"I think probably, on balance, would that be my preference. If the numbers work? Then yes, probably it would," she told Today.

The battle between the SNP and Labour for the general election has been an increasingly tense one since the independence referendum last autumn.

With the polls suggesting many traditional Labour supporters have switched to the SNP, leading figures in the party have said they would be keen on working with, and influencing a Labour government - and also said they would oppose any Conservative government.

Leader Nicola Sturgeon said recently: "The bottom line here is, if Scotland wants to have that influence, that power, that clout in Westminster, then the only way to get it is to vote SNP.

"Scotland's experience of Westminster politics up until now is either that we have to put up with Tory governments we didn't vote for or we get Labour governments that end up implementing Tory policies.

"If there's real SNP strength in the House of Commons we can influence progressive change."