You read the candidate web pages, and everyone sounds exactly alike - for jobs, for accountable government, against crime, for education, etc.
The only way to choose is to read their endorsements.
When you see women's groups, eco-groups, and public sector unions rally around one candidate, you know you've found the Democrat.
This comes under the category of a two edged sword. There is an increasing segment of the voting public who will vote for the alternative to a D candidate regardless of competency. Their assumption is that all D candidates are unacceptable.