I phone banked at the SEIU hall in San Francisco a couple hours ago for Phil Angelides. There were Schwarzenegger supporters and Angelides supporters out front demonstrating. We might be able to use the Schwarzenegger supporters against themselves.
When I got responses out of my precinct, they were yeses. I didn't have any nos or undecideds. But I could hear those people out on the street and I was wondering if the citizens I was calling could too.
I didn't think of how to deal with that question until after I left. If people ask "what's that noise in the background" or "are you at a protest", it might help to say something like:
There are supporters of both [our candidate] and the opposition (let them pay for their own Name ID) outside demonstrating. But it just shows how important this election is. People are care so much about [issues your campaign is hilighing] that people talking on the phone is a big deal to them. [your candidates] opponent is running scared, otherwise his/her supporters wouldn't bother coming out today. It just shows that we can win this, but we need your help. Can we count on you to vote for [our candidate] on [date of election]?
So yeah. Don't fall into the trap of the demo being a bad thing. Reinforce the motivation of the crowd, reframe their passion and use it to back your message.
Let the GoP demonstrators yell until they're mute. They're getting the vote out for your candidate.