Party leader Ruth Davidson told former Liberal Democrat and Labour voters who have left their parties they can “unite” around a Scottish Conservative party promising no deals with the SNP.
She was speaking in the target seat of Berwickshire, Roxburgh and Selkirk.
The Conservatives’ John Lamont is hoping to capture the seat from Liberal Democrat Michael Moore, but the SNP is also in the running.
Ms Davidson said in a speech in Melrose yesterday: “I know that many people voted Liberal Democrat or Labour in the past and are now looking at those parties and wondering what to do.
“My question is: Why join a sinking ship?
“My message to all those people is that the Scottish Conservatives are on the up, we have the momentum going into this election, and we can represent your values, and fulfil your aspirations.”
The Conservatives in Scotland will launch their biggest ever “voter contact” campaign in the country this weekend.
Ms Davidson added: “The Scottish Conservatives are speaking to Scots right across the political spectrum.”