Everyone’s a comedian so here’s some actual advice.
TLDR: be polite but firm, know what you’re asking for.
Lots of activism and lobbyist groups have the concept of an “ask”, or what you’re attempting to get out of the negotiation. Have a solid, easily understandable ask that is generous enough to withstand a bit of pushback from the other party, who will almost certainly try to negotiate the other direction. Also, when you deliver a statement, question, or ultimatum, wait for the other person to respond to it, even if there’s a couple seconds of silence in between. Conventional wisdom says the one who speaks first in these moments is displaying insecurity and is less sure of their ask or position in the negotiation.