Generally in recent years given the way voters are distributed, the Republican candidate has an advantage with the electoral college such that a Democrat can't merely win the popular vote.
In 2020, this electoral college bias was pretty large such that Biden won the popular vote by 4.5%, but only won the tipping point state Wisconsin by 0.6%.
In 2024 currently it is only a slight bias. So Biden could win the electoral college even with only a ~1-2 point lead nationally if this stays the same.
In fact that's more or less what happened in 2022. California and New York were closer than expected while Texas and Florida weren't. But Democrats did pretty well across the country such that the red wave turned into more of a red ripple.