That's not necessarily true.
As long as you decide that anyone who disagrees with you on a single issue represents all that is bad or evil in the world, then you have absolutely no chance of ever changing their minds because you have decided that they are "the enemy".
I don't believe that 31% of the US population are "hardcore Leftists". Of that number, I'd guess that no more than a few percent are. Some have genuine concerns about this specific law and voted their conscience, and the vast majority are just riding along on their "feelings" without even thinking about it -- this latter group can be converted and must be converted if there is any hope of ever turning around this country.
We have been changing minds for the past year and a half. The figure used to be at 51%. These 31 % are hard core, not going to change.