"Okay, so both parties are bad, but what else can we do other than vote?"
There are going to be a lot of disenfranchised liberals that have lost faith in electoralism. Rather than allow the people to fall into doomerism or denial, what advice would you give people who are realising that western democracies are broken and that voting for the lesser evil is impossible? What action would you tell them to take?
"Real politics happens well before the elections, and that's why you will never have good options. You are always choosing betweens presets which have long been decided, and which are not going to solve the climate, queer, women's, etc issues.
We need to meet that political power before elections, then, to have any effect. But that requires understanding the systems which we are up against, or else we will only be doing the result-less protests of the past 40 years again.
You interested in learning more about the systems?"
This is a discussion which requires the active participation of the lib (them backing down at this point makes it obvious that they are not the target group for us).
It includes the things that are probably most important to a lib willing to listen (replace as needed with "wage problems" etc)
It shows that you're not asking to do repeats of the unsuccessful movements of westerners in the past years (because libs would latch onto that and be started wrongly or fill up ranks with useless people).
Follow-up convos about how the problems are based in imperialism and capital.