Answer:
They provide the funds and publicity so a candidate with similar views of the party are elected. The leaders of that specific party want to make sure a competent candidate that will enforce their beliefs are elected, therefore they provide money to help them win. Political parties also help the voter to understand what a candidate's stance on certain issues are, even if they have never seen the candidate before. (Example: If you see an R next to a potential U.S. president you know they will be strict on illegal immigration. If there is a D however, you know they will be more loose about illegal immigration.)
Step-by-step explanation: