A

A challenge that modern presidents face is leading their political party.

Explanation:

The President of the United States is the de facto leader of his or her political party, as he or she has to win the internal election before the national vote happens. He or she also has a variety of powers as defined by Article II of the Constitution.

Donald Trump Attending a Republican Party Gathering.
Donald Trump Attending a Republican Party Gathering (Source: https://cdn.theatlantic.com)

The appointment of many officials is within these abilities, though the Congress has the power to veto the candidacies proposed by the President. As such, part of the President’s goals is to promote the position of his or her party by appointing capable and agreeable members to vital positions.

The President can also issue executive orders, grant pardons, and recognize foreign nations. However, none of these powers and duties are as essential as party leadership, primarily due to the rarity of their occurrence.