The role of the president has evolved over time because

the needs of the nation have changed.

the role of the executive branch has changed.

the role of Congress has changed.

the needs of the chief of staff have changed.

The needs of the nation have changed.

Explanation:

As we know, human beings live in constant evolution. This evolution promotes several changes in society that reflects changes in a nation.

These changes bring about improvements in the nation, but they also promote the emergence of new needs, which requires political and governmental changes that address the changes, needs and new characteristics of the nation.

This is one of the main factors that provoke changes in government positions, not only in the position of precidente, but all positions related to the political management of the nation.

For this reason, we can say that the role of the president has evolved over time because because the needs of the nation have changed.

Answer: the needs of the nation have changed.