Anti-independence campaigners have spent tens of thousands of pounds in the past week calling for tactical voting to prevent the Scottish National party winning a Holyrood majority. At least five pro-UK groups have bought newspaper adverts, mobile ad vans and electronic billboard sites, and numerous adverts on Facebook, urging voters to support election candidates most likely to beat an SNP candidate. Scotland Matters, a group co-founded by Prof Hugh Pennington, a bacteriologist in Aberdeen who rose to prominence during E coli food poisoning outbreaks in the 1990s, registered with the Electoral Commission so it can spend up to £75,000 on tactical voting adverts during the election. Spending by other groups includes £2,000 on an Edinburgh-focused Facebook ad promoting the VoteUnion tactical voting tool, which has been seen at least 125,000 times; at least £1,500 spent on Facebook by ThinkScotland, a blog edited by the former Conservative MSP Brian Monteith, to promote VoteUnion’s guide ; and Young Unionists, a new group with no clear indication of who is behind it, placed a similar ad on Tuesday. This increase in activity highlights growing anxiety among anti-independence campaigners that Nicola Sturgeon’s personal popularity during the Covid crisis will lead to a significant pro-referendum majority in Holyrood. While support for independence has fallen back, with most recent polls showing a clear lead for a no vote, the polls show the SNP is on course to win the election comfortably. That will underpin Sturgeon’s calls for a fresh independence referendum by the end of 2023. It remains unclear whether the SNP will win an outright majority, but with the polls suggesting the Scottish Greens could get 10 seats, doubling their number, pro-independence parties are expected to hold the most Holyrood seats. Pennington said Scotland Matters, which includes a Liberal Democrat councillor, Tory activists and pro-union businessmen, existed solely to prevent an SNP majority. “Across the country as a whole, tactical voting is obviously one of the ways forward to basically harm the SNP, not to put too fine a point on it,” he said. Labour and the Conservatives are officially urging their supporters to avoid tactical voting but the Liberal Democrats are relying on it to hold some seats and win back others. Ed Davey, the Liberal Democrats’ UK leader, has urged anti-SNP voters to back the Lib Dem candidate in Caithness, Sutherland and Ross, where the SNP is defending a 3,913 vote majority. Their campaigns have been overshadowed by Alex Salmond’s call for SNP voters to back his new party, Alba, on the second, list vote, in a tactical vote to secure what he describes as a “pro-independence super-majority” at Holyrood. Salmond claims that more than 900,000 votes cast for the SNP’s list candidates in 2016 were “the ultimate wasted vote” because they led to only a handful of MSPs being elected. Under Scotland’s hybrid voting system, which has 73 constituency seats and 56 regional list seats, parties which win large numbers of constituency seats, such as the SNP, are not allocated top-up seats from the lists. Salmond told the Guardian he believed this argument was “striking with lots of people”. The former first minister said: “There are a lot of indications that people are now better informed than they were at the start of this campaign … and that lots of people who understand that see the system for what it is and are intending to vote for Alba on the regional list”. SNP candidates report that, while voters are asking more questions about the two part voting system this campaign, their growing awareness is not necessarily benefiting Alba, but the Scottish Greens instead. Sturgeon herself has accused Alba of “gaming” the voting system, and said she would not work with Salmond if he is elected on Thursday. A recent Scotland Matters advert shows Salmond controlling a puppet of Sturgeon, who in turns controls a puppet of Patrick Harvie, the Scottish Greens co-leader. The former Respect and Labour MP George Galloway is leading a pro-UK tactical voting campaign with his new All for Union party, chiefly in the south of Scotland where Galloway is standing for election on the list. Opinion polls show minimal support for his group.