WASHINGTON (AP) — They are two tiny Caribbean states whose intractable problems have vexed U.S. presidents for decades. Now, Haiti and Cuba are suddenly posing a growing challenge for President Joe Biden that could have political ramifications for him in the battleground state of Florida.

Cuban demonstrators have taken to the country's streets in recent days to lash out at the communist government and protest food shortages and high prices amid the coronavirus pandemic. In Haiti, officials are asking the U.S. to intercede in a roiling political crisis after last week's assassination of Preside...