Nicola Sturgeon has suggested Theresa May called a snap general election before alleged Tory expenses fraud in 2015 "catches up with her".
Scotland's First Minister said the Conservatives should not be allowed to escape accountability for any "misdemeanours" in a speech to the Scottish Trades Union Congress (STUC) in Aviemore in the Highlands.
There are claims against the Conservative that concern improperly reported election spending during the 2015 election and in three by-elections in 2014.
Ms Sturgeon said: "We are, of course, at the start of a general election campaign.
"A campaign called by the Prime Minister last week for one purpose and one purpose only: to strengthen the grip of the Tory party and crush dissent and opposition, and to do so before possible criminal prosecutions for alleged expenses fraud at the last general election catches up with her.
"Whatever else happens in this election, we should not allow the Tory party to escape the accountability for any misdemeanours that may have led to them buying the last general election."
Ms Sturgeon said the Tory vision for the future of the country "should be ringing alarm bells loudly and clearly across Scotland right now".
She said: "Because, make no mistake, and I think it's obvious to see, the hardliners have taken over the Tory party and now those Tory hardliners want to take over the country as well.
"It's no surprise that Ukip right now is losing support to the Tories because the Tories are now threatening to take the UK in a direction that a few years ago Ukip could only have dreamed about, but it should alarm all of us.
"Whatever our politics, we should all stand up against that rightward drift of the country that the Tories are determined to effect."
Ms Sturgeon continued: "Scotland knows, we know from long experience, that there has always been a cost to voting Tory but the price at this election has never been higher, and it will be those that are least able to pay that price who will bear the biggest burden."