CNN — The first phase of the 2024 presidential primary season is officially underway, bringing with it a cavalcade of early polling designed to answer a seemingly basic question: whether President Joe Biden and his predecessor, Donald Trump, have the support of their respective parties.... That topic, though, is more complicated than it seems, reflecting voters’ complex attitudes toward the two men, which in both cases fall far short of either an enthusiastic endorsement or a definitive rejecti