I feel like targeting politically active people who already have some allegiance is a waste of time when there are millions of people without a political allegiance who are much easier to sway (most of the time)
Unless you can easily infiltrate leadership, there's not much you can do. Libs generally aren't going to be swayed if their leadership isn't on board.
Imo the best adult targets for radicalization are people who haven't quite identified their own politics, but are in a position to benefit tremendously from socialism or even just progressive ideas. Everyone else is a waste of time, you'll often find them digging in deeper the more you try so it requires a lot of subtlety and time.
The libs who can be convinced will often convince themselves over time anyway. Sometimes you can speed it up, but again that can sometimes backfire. People will often regress into their comfort zone instead of confronting the levels of cognitive dissonance that can come with radicalization. I think that's probably why it's easier to get people who don't engage with politics/ideology much at all, but already think the US sucks. They don't have to undo an existing idea so much as process a new one, which is always easier.