We can colonize the Universe without any actual human leaving this planet. That would be the most efficient way, both in terms of resources and speed. It has been calculated a number of times that sending a fleet of self-replicating probes would result in the colonization of the entire galaxy in a surprisingly short time - 0.5 to 10 million years, depending on who you ask.

We need to stop thinking in terms of the next general election and start thinking about a more long-term future.