Trump doesn't have to bluff anything. I've seen a few comments now suggesting that Zelenskyy somehow has the upper hand and is negotiating from a position of strength while Trump is weak.
Ukraine and Zelenskyy have absolutely no leverage over Trump. Zip, notta.
I hope Ukraine wins this war. I hope Putin pisses off Trump and Trump resumes full support for Ukraine. I hope Putin is destabilized and better leadership replaces him.
But Zelenskyy is no position to "call" anything and Trump has no reason to bluff.
Gotcha. I see better where you're coming from now. Yeah, Zelenskyy needs to be very very careful.
edit: mixed up commenters but the comment above is insightful and turn out right.