Glasgow - All eyes will be on Scotland on Thursday as the Scottish National Party looks set for a landslide victory north of the border in Britain's general election, a result that could hand it the role of kingmaker.SNP leader Nicola Sturgeon said the vote could be a "watershed" where Scots reject Labour, the party that has represented them for generations, fundamentally altering the balance of power in British politics."The weather may be a wee bit dreich [miserable] in Edinburgh this morning but the outlook for Scotland is sunny, very sunny," she told a final campaign event on Wednesday surrounded by cheering supporters.Across Britain, Thursday's vote remains too close to call, with Prime Minister David Cameron's Conservatives and the opposition Labour party neck and neck in the opinion polls.But in Scotland, it is a very different story.Despite losing last September's referendum on Scottish independence, the SNP looks on course to win more than 50 of the 59 Scottish seats in the House of Commons, up from just six at the last election in 2010.Most of these would be at the expense of Labour, which won 41 Scottish seats five years ago. Losing these would make it very hard for Labour to win a majority in the 650-seat House of Commons.With the Conservatives also likely to fall short of a majority, both sides may well have to turn to smaller parties to form a government, giving the SNP and its anti-austerity message a strong hand."Whether [you] voted Yes or No in the referendum or have never voted SNP before, it is an opportunity to come together as a country and vote to make our voice heard at Westminster," Sturgeon said. Government held to ransomLabour leader Ed Miliband made a final effort to stop supporters defecting on Wednesday, insisting he understood the "patriotism and pride" of Scots, and warning that backing the SNP made a Conservative government more likely."If I'm prime minister I will hold Scotland's interests in my heart and my head," he said.He has insisted there will be no deals with the nationalists after the election, whether for a formal coalition, such as that agreed five years ago between Cameron and the smaller Liberal Democrats or a looser arrangement in parliament.But without a parliamentary majority, he may be forced to rely on the SNP if he wants to become prime minister.The Conservatives have played on concerns in England about the influence of the Scottish party, which remains committed to the break-up of the United Kingdom."This whole thing about a Labour government backed by the SNP in government people feel deeply uneasy about, because it would be a government held to ransom by a group of people that don't want the UK to succeed," Cameron said Wednesday.There is also the prospect that a stronger SNP could press for another referendum on independence.Sturgeon insists her party will play a "positive and constructive role".She has made clear she will seek to block the Conservatives forming a coalition or minority government, but insists that she would not give a Labour government an easy ride.Labour is committed to continuing Cameron's austerity programme but on a reduced scale, while the SNP says it would raise public spending each year."We can lock the Tories out of government but then we can make sure that the Tories are not simply replaced by a Labour Tory-light government, they are replaced by something better," Sturgeon said.The horse-trading is likely to begin within hours of the results rolling in.All the main party leaders, including Sturgeon in her capacity as Scottish first minister, are due to attend a ceremony in London on Friday marking 70 years since the victory over Nazi Germany in World War II.