How to work with Liberals/Leftists? He has some good advice:
Compromise is potentially constructive only when it's strictly about means: i.e., when the two sides angling toward a compromise sincerely agree on the end to be sought, and are both willing to allow that they might be wrong about what means would best serve that end. Under those conditions, everyone involved will be watching the outcome and judging the means applied by that standard alone. When the ends are opposed to one another,compromise must disserve one or the other. It cannot be any other way.
If your end is political liberty -- the maximum possible freedom from coercion or constraint for peaceable persons -- there's absolutely no reason to "dialogue" with persons whose end is an expansion of State power. Compromising with statists means promoting their end, which is the exact opposite of your end. Yet many a freedom-minded person will feel a tug toward such a "dialogue," and the ideal of compromise, despite the clarity of the above. This is the Nice-Guy Trap in action.
We're indoctrinated practically from birth about the goodness of "sharing," and how Nice Guys should "try to see both sides" -- of everything. Nice Guys mustn't declare others to be The Enemy even when The Enemy has already done so in the plainest possible ways. That's because confrontation is bad, don't y'know. At any rate, it's unpleasant, which in modern "thought" amounts to the same thing.
Hidden beneath the Nice-Guy Trap is a pair of steel jaws that can snap any principle cleanly in half. This is so obvious as to be tautological: He who compromises on principle has surrendered it to some other end.
There's more, and I suggest you read it.