The simplest way for him to have success would be to require his supporters to disarm. US jails are teeming with violent felons who support liberalism at near unanimity.
Crime reduction aside, wouldn't it be a show of good faith and noble intentions if all Democrats turned in all of their arms voluntarily? Just to show us the wisdom of their intentions? After all some 40+% of Dems are gun owners according to statistics. It should only take a couple of years to show how dramatically things have changed.