I think that is definitely the wrong question to ask. Most people are going to interpret that question as "would you like me to tell someone else to contact you and ask for money, time, whatever?".
This is how I canvass...
Hi my name is X. I live in the neighborhood. I'm canvassing for the upcoming primary. Will you be voting?
What are the most important issues for you this election?
Have you decided on a candidate or are you still deciding?
Do you know about Ron Paul?
- Be prepared to answer questions concerning Ron Paul's positions on their issues
- Be prepared with slimjims that address their issues (if possible)
- Suggest that they visit ronpaul2008.com for more info or contact HQ
- Tell them about any upcoming events or debates where Ron Paul will be present
You're trying to identify potential supporters, but don't expect them to decide on the spot. Your trying to have a conversation with them about why you think Ron Paul is the best candidate. But most people (if they're still deciding) will want to learn more about Ron Paul's positions, even if they've heard some of them from debates or from you.
Your question might be appropriate if they already know a lot about Ron Paul and are obviously very interested toward getting involved. But I've never ran into anyone like that who wasn't already involved with the campaign's efforts somehow. If they're eager to get involved, they'll let you know. Leave your contact info with them, if you're comfortable doing that.