With Labor gaining, it looks like this could end up as some sort of 2017 redux, where conservative PM calls for new elections in light of strong polling numbers, but then ends up with a bare victory and another hung parliament as leftwing voters come home to Labor.
Perhaps Johnson will be able to stand his ground better than May, but if indeed we do get another hung parliament and Labour can't form some sort of coalition to secure power we're right back to where we were before and the Brexit demons continue to haunt the country.
I guess thats Johnson's argument really, but it doesn't paint a great picture to the electorate: "vote for me or else we're going to be trapped in perpetual gridlock"