You’re right: “in certain situations” is the key here.
It really means nothing without seeing an actual outline of a plan. We already have single-payer care in a lot of situations.
Even Rush Limbaugh once suggested giving everybody catastrophic coverage. That could be interpreted as single payer, but only in a sense.
We need to see more, but immigration is still the major issue. We dare not lose on that one, and few Republican candidates are willing to take as strong as stand.
Frankly, as much as I despise single payer, I’d take that over a candidate who’s wobbly on immigration.
He has repeatedly praised single payer.