The compatibility of the National Popular Vote Interstate Compact with voting systems other than plurality is an issue in the early stages of being assessed. The Compact provides that: Approval voting is almost certainly compatible with this provision, and it is believed that instant runoff voting, Condorcet, etc. could still be implemented via another compact. Ballots cast in those states not participating in preferential voting could be counted as bullet votes (i.e. ballots with only a first choice selected.)