Final answer:
Political parties and leaders in presidential systems like the U.S. operate independently, which can lead to the emergence of strong or populist leaders and divided government. In parliamentary systems, the party in control of parliament typically supports the government leader, creating a unified policy agenda but not immune to populism.
Step-by-step explanation:
The relationship between political parties and leaders varies significantly between presidential systems and parliamentary systems. In a presidential system, such as that of the United States, the president is elected separately from the legislative body and may belong to a different political party, which can lead to a divided government and potentially makes legislation difficult. This independence of the executive from the legislature can facilitate strong or populist leaders and presents distinct challenges to democracy, as seen with former President Trump's administration. In contrast, a parliamentary system features a tighter integration between the executive and the legislative branches, with the leader usually being the head of the majority party in parliament. This ensures that the government generally has a cohesive policy direction, but can also mean that populist leaders could emerge within parliamentary parties.