The constituency of Stirling, which Nicola Sturgeon visited on Tuesday, is the SNP’s top target at this election.
Conservative candidate Stephen Kerr is defending a majority of just 148.
A swing to the SNP of only 0.2% would see the seat change hands.
It is one of the most marginal constituencies in Scotland – and one of a number of seats the SNP are determined to take from the Conservatives, having lost them at the 2017 election.
Stephen Kerr won the seat in 2017 on a swing to the Tories of 11.4%.
The result was so close that a recount was necessary.
This time the SNP will be hoping for the sort of swing that will see them take Stirling easily, along with the likes of Gordon (2.5%), Angus (3.3%) and Moray (4.4%).
For the Conservatives, holding seats like Stirling will be a vital test of the party’s popularity in Scotland.
It would also help to offset potential losses elsewhere in the country.
Labour held Stirling continuously from 1997 to 2015, but finished third in 2017.
The party isn’t really in contention this time, as Stirling is now very much a two-horse race.
Along with the SNP, Conservatives and Labour, the Liberal Democrats and Greens are also standing in the seat.
Stirling voted 67.7% Remain in the EU referendum – the fourth highest Remain vote in Scotland, and the 20th highest Remain vote in the UK.