LABOUR attempts to undermine the SNP's core election message have fallen flat, even among the party's own supporters, according to a new poll.

A Survation survey found almost four times as many people believed more SNP MPs meant "Scotland's interests will be better represented" as thought the opposite.

Most supporters of Labour, the LibDems and SNP agreed, with only Tory supporters believing a large SNP bloc in the Commons would diminish Scotland's voice.

Most people who voted No in the independence referendum also agreed.

The SNP's main campaign message is that a large group of Nationalist MPs would make Scotland's voice stronger than ever at Westminster.

The poll suggests Labour attempts to undercut this by ruling out a deal with Nicola Sturgeon to marginalise the SNP have failed, and voters still see the SNP as highly relevant to what happens at Westminster after May 7.

The SNP-commissioned poll asked whether people thought "electing more SNP MPs to the House of Commons at the general election on May 7 will mean Scotland's interests" would be better or worse represented.

Overall, 63% said things would be better, 16% disagreed, and 21% were undecided.

At least 60% of people in all age groups agreed, as did 58% of those who voted Labour in 2010, 71% of people who voted LibDem and 90% of SNP voters.

Only 4% of SNP voters, 15% of LibDems, and 20% of Labour voters disagreed.

Among Tory voters in 2010, only 34% agreed more SNP MPs would enhance Scotland's interests, while 42% disagreed and 23% were undecided.

How people voted in the independence referendum was a key factor, with 90% of Yes voters agreeing with the proposition, 2% disagreeing and 7% undecided.

But even among No voters, the largest group, 45% agreed with the proposition, compared to 26% who disagreed and 29% who were undecided.

The belief that more SNP MPs would help Scotland's representation was also shared by two-thirds of socio-economic classes ABC1, who mostly voted No last year.

However there was some solace for Labour among the findings.

In Glasgow, Central Scotland, and Mid-Scotland and Fife, large numbers of voters were undecided on the issue, especially those in socio-economic classes DE.

Angus Robertson, the SNP's general election campaign director, said: "There is a very big majority for our case that more SNP MPs at Westminster means that Scotland's interests will be better represented - including among people who voted Labour and Lib Dem at the last General Election. These figures help explain the size of SNP support in this election, and also its strength."

Survation polled 1015 Scots aged over 16 online from April 22 to 27.

The Scottish Tories also released some of their polling figures yesterday, showing Ruth Davidson was the most trusted of the three Unionists leaders in Scotland.

YouGov asked 1162 people last week which of the three they trusted most "to keep Scotland part of the United Kingdom".

Davidson came top with 29%, Labour's Jim Murphy was most trust by 20%, and LibDem Willie Rennie managed just 3%.

However the same number of people who backed Davidson, 29%, said they trusted none of the three to keep the Union intact, and 18% were undecided.

Davidson, who only became an MSP in 2011, is seen to have had the best personal campaign after Sturgeon north of the border.

But her personal ratings have not been matched by an uplift for her party.

A Lord Ashcroft poll last week suggested the Tories would lose their only Scottish seat, Dumfriesshire, Clydesdale and Tweeddale, to the SNP.

However the Tories could pick up another Borders seat from the LibDems.