GORDON Brown has made a final, passionate plea for Scots to back Labour, warning a vote for the SNP "can only help the Conservative Party".

In a powerful address, evoking some of the barnstorming speeches he gave in the closing days of the independence referendum campaign, the former prime minister urged voters not be "confused" by SNP claims that a vote for the Nationalists would usher in a Labour government after tomorrow's election.

Mr Brown rallied supporters in Glasgow alongside Scots Labour leader Jim Murphy and shadow Scottish secretary Margaret Curran on a hectic day of campaigning across Scotland.

Visiting a nursery in Livingston, Nicola Sturgeon said voters had "48 hours to get the Tories out".

Repeating her promise to work constructively with Labour, she said: "The fact of the matter is, if there's an anti-Tory majority on Friday morning, I want to see that anti-Tory majority come together to get the Tories out, but then make sure that it's replaced with something better."

Willie Rennie, the Scottish Liberal Democrat leader, said he wanted his party to have a role in the next government.

Scots Tory leader Ruth Davidson, who boarded a steam train in the Highlands, said her party would "keep the UK intact".

Mr Brown was cheered by the Labour faithful as he told them: "I come not as a candidate but as a volunteer".

He admitted his party, which faces devastating losses to the SNP in Scotland according to the polls, has faced a "difficult fight" but he said many Scots remained undecided and urged activists to campaign for every vote.

He accused the Tories of "putting the Union on life support" by turning the election into a battle between English and Scottish nationalism.

But in his main message he insisted voting Labour was the surest way of defeating the Tories and putting Ed Miliband in 10 Downing Street.

He said voters had been "confused" by SNP claims that a vote for them would put Labour in power.

"We have to explain to them a vote for the SNP can only help the Conservative Party.

"I find when I explain that to them, and others explain that to them, they are prepared to come back to Labour," he said.

"Every vote counts and it has to be a Labour vote. I find it perverse logic for the SNP to say you can have a Labour government without voting for Labour candidates."

Repeating Mr Miliband's promise not to enter any kind of pact with the SNP, he added: "The reason why we can't do a deal with SNP is not expediency, it's on principle.

"We can not have a deal, or a compromise, or a tie-in with a party that doesn't share the principles of solidarity."

Ms Sturgeon will end her week-long helicopter tour of Scotland in Edinburgh today.

Speaking ahead of her final day of campaigning, she said: "On Thursday morning, Scotland has the opportunity to make its voice heard at Westminster like never before.

"I know that a strong team of SNP MPs will have Scotland's interests at heart first, last - and always.

"In these final hours I will be campaigning tirelessly to get the message out.

"And I truly hope that Scotland will unite to put its trust in the SNP to bring about the progressive change that people across the UK are waiting for."

Nick Clegg will take his battle bus to four Scots constituencies the Lib Dems hope to hold as he end his campaign trip from Lands End to John O'Groats.

Mr Murphy will visit a nursery in Inverclyde on his last day on the stump.