There are 258 million in the US over 18, with 60% ACTUALLY living paycheck to paycheck. We need about 10 million from those who aren't. It's actually not a very big hurdle. The hardest part is finding people who will actually sacrifice some of their comforts instead of claiming they can't afford to
The hurdle is that roughly 34% of those 258 million are somehow in favor of all of this. We don't know how that changes the "60% living paycheck-to-paycheck" figure, so that might not be accurate.
I'm guessing pretty evenly split down the middle, but the problem still remains that a lot of people who could do more simply don't want to have to. It's a sad statement on our Democracy, but complacency and general laziness/comfort is more of a hurdle than number of people available