Glasgow South West MP Ian Davidson was said to have placed the ad in a free newspaper, The Govan & Glasgow South West Press, distributed to 20,000 homes in his constituency.
Scottish Conservative leader Annabel Goldie said she was sent a copy of the newspaper anonymously.
She said: “If that is what the Labour Party in Scotland is reduced to, that to me says it all about the complete vacuum at the heart of their policy.”
On the eve of the Scottish Parliamentary election, Miss Goldie claims at least one family has switched to the Tories: “I told them about the advert and this erstwhile Labour supporter said: ‘I‘ve heard enough. The Conservatives are getting my vote’.”
Editor and publisher of the freesheet John Maclean said: “I thought it was quite funny and I knew that no one would take it seriously, so I left it in... I apologise if it has damaged the Tories’ chances of winning a seat in the south of Glasgow, although I don’t think they had much chance of doing that anyway.”