Thursday’s Holyrood election could be crucial in determining the future of Scotland in the UK.

While Nicola Sturgeon’s SNP is certain to emerge as the largest party after all the ballots have been counted, the question of whether they will get an overall majority is on a knife edge, according to some polls.

Winning a majority in the 129-seat Scottish Parliament is tricky, due to the proportional representation system used to elect MSPs.

A total of 73 constituency MSPs will be returned in the election, with the remaining 56 coming from the regional list ballot, which is used to try to bring the number of representatives each party has in line with their share of the vote.

The regional list votes will be critical in determining the make-up of the new parliament, and as polling day approaches, Ms Sturgeon has been urging voters to back her party with both their ballots.

The Tories and Labour have also been stressing the importance of the regional votes as the campaign reaches its final stages.

Scottish Labour’s new leader Anas Sarwar has fought an energetic campaign, as he seeks to oust the Tories from second place at Holyrood and make his party the official opposition.

Throughout the campaign he has argued that the coronavirus pandemic and how Scotland will recover means now is not the time to think about the constitution.

Mr Sarwar has put his focus firmly on recovery, putting forward plans for jobs, the NHS and education.

But the Scottish Tories, led by Douglas Ross, insist that only a vote for them can stop the SNP from winning a majority and pushing ahead with a second independence referendum.

The Conservative campaign has focused strongly on the need to stop such a vote, with Mr Ross arguing his party’s success in preventing an SNP majority in 2011 means they are the only party that can be trusted to do this.

Meanwhile the Scottish Liberal Democrats, whose campaign message has been to put recovery first, are hoping they can gain seats.

Leader Willie Rennie hopes to win the backing of previous SNP supporters who agree the time is not right for a second referendum.

In addition to this he believes his party can win votes from the Tories, arguing that those who previously backed the Conservatives because of Ruth Davidson will reject the “darker” politics of Mr Ross.

The Scottish Greens, who also support independence, are pushing to increase their numbers at Holyrood.

If the SNP fails to win a majority on its own it is likely that the Greens – led jointly by Patrick Harvie and Lorna Slater – will provide the MSPs needed for a majority in the Scottish Parliament for independence.

There is also the prospect of more pro-independence MSPs being elected from Alex Salmond’s new Alba Party.

The former first minister was unveiled as the leader of Scotland’s newest political party at the start of the election campaign.

He has claimed that Alba MSPs could help form a “supermajority” for independence in the next parliament, but opinion polls have been doubtful about whether the new party, which is only standing candidates on the regional list, will attract enough support to win any MSPs.

Ms Sturgeon has made clear she will not work with Mr Salmond should he again be elected to Holyrood, after the SNP leader and current First Minister had a very public falling out with her former friend and mentor over the way her Government handled sexual harassment allegations made against Mr Salmond.