I'm sorry, I wasn't trying to be difficult or anything...but I really don't have much idea as to what "grassroots style issue campaign" means in a practical sense. Data services I get, what sort of things are grassroots?
Ah, understanding at last.
Grassroots campaigns are basically campaigns to influence elected official positions on key bills, etc. For instance, you're a defense contractor and you're trying to win a very important bid. You need congressional support, so you hire a firm to get people to call their member of congress and get that member to support you for the contract. Another example might be that the Governor wants to cut money from the budget, including $21 million that is used to fund Veteran Services Officer positions in the Employment Development Department.
Now, traditional grassroots is where you get normal people to write in and call their elected officials (say veterans calling the Governor). You can also go for a grass 'tops' approach where you get key influences in a district (say the top 3 major contributors to a Congressmember's last campaign) to call and influence them in your favor. Different clients require different strategies, and all of those strategies require ways of contacting the target people.