Uh, no.
I would hope that an attempt to do so would involve the rest of the world to rally to our defence. At which point I would join the resistance to defend the country. I DO NOT WANT to live in the U.S. thank you very much.
I don't actually support forcibly annexing Canada. I only support our two countries combining because I like Canada so much. As TNF notes above, realistically, I support completely open borders between the US and Canada without restriction (something like the Schengen Agreement). There are certainly other issues, such as a common currency, where our two countries could work together.
Open borders would work. I'd be wary of a common currency though. Our economy is dragged down enough when the US is recession.