Pollsters have said that “razor-thin margins” will determine whether Nicola Sturgeon wins an overall majority at Holyrood on Thursday.
Research by Opinium found support for the SNP was down slightly in both the constituency and regional list section of the ballot.
In the constituency vote, support for the SNP was at 51%, a drop of two points from the previous poll in April, with both the Tories and Labour making gains.
Douglas Ross’s Scottish Conservatives were up two points to 23%, with Labour up by one point to 19%.
On the regional ballot, SNP support dropped by three points to 41%, with the Tories up by one point to 23% and Labour remaining steady on 17%.
The polling, for Sky News, projected the SNP could win an outright majority with 67 seats, with the Conservatives forecast to hold on to second spot with 29 MSPs, ahead of 20 for Labour.
Support for the Liberal Democrats was at 7% in the constituency section of the ballot and 6% on the regional list.
Meanwhile, the Scottish Greens, who run mainly on the list section, were at 8% on this, ahead of former first minister Alex Salmond’s new Alba Party, which was on 3%.
Chris Curtis, senior research manager at Opinium, said: “The campaign finishes much where it started, with razor-thin margins set to decide whether Nicola Sturgeon can govern alone or will need the backing of other pro-independence parties.”
A total of 1,015 voters were questioned for the poll, with the research taking place between April 28 and May 3.
On the key issue of Scottish independence, Opinium found voters were split 50/50 – down from 51% support for Yes in last month’s poll.
Less than three out of ten (28%) of those questioned wanted a referendum in the next two years, with support for a second independence vote in this timescale down by five points on the previous study.
Meanwhile, a further 14% of voters think a fresh vote on independence should happen in the next two to five years, a drop of two points.
Curtis said: “Our latest polling shows the Scottish public are not necessarily keen on another Scottish independence referendum.”
He said that even if Sturgeon did succeed in winning a majority, just 43% of people want another referendum in the next five years, compared to 50% who are opposed to this.
Curtis added: “We have also seen Labour voters harden in their view over the campaign, with just 24% willing to back one in those circumstances.
“Regardless, Sturgeon will argue that a good result this week gives her the mandate to put the question back to the Scottish people, demonstrating just how important this week’s vote will be for the future of the Union.”
Sturgeon remains the most popular of the party leaders, with net approval rating of +17, but this is down from +23 last month.
The new Scottish Labour leader Anas Sarwar has seen his approval rating continue to grow, from +10 in April to +13.
Ross has a rating of -26, although this is up from -31 the previous month. Salmond is the least popular of the leaders, with a net approval rating of -70.
SNP depute Leader Keith Brown said: “Every vote counts in this election. The outcome is on a knife edge and Labour and the Tories are teaming up to try and stop Scotland making progress.
“Anything less than both votes for the SNP risks leaving Scotland’s future in the hands of Boris Johnson and the Tories instead of the safe hands of Nicola Sturgeon.”
Annie Wells, Scottish Conservative candidate for Glasgow, said: “More polls show that only the Scottish Conservatives can stop an SNP majority, stop another independence referendum and get all of the focus back on rebuilding Scotland.
“Seven polls in the last week have demonstrated that voting for the biggest opposition party, the Scottish Conservatives, is the only way to stop an SNP majority.
“We can only get the Scottish parliament 100% focused on Scotland’s recovery if pro-UK, anti-referendum voters come together and lend their peach party list ballots to the Scottish Conservatives.”