The Vice President's primary constitutional role is to serve as the second-highest-ranking official in the U.S. government, just below the President. This is established in Article II, Section 1 of the U.S. Constitution. 

ABOUT THE VICE PRESIDENT

The Vice President presides over the Senate but can only vote to break ties. In this role, they have a crucial function in the legislative process, as they can cast tie-breaking votes on bills, nominations, or other matters. 

One of the most critical roles of the Vice President is to be next in line to assume the presidency in case the President is unable to perform their duties due to death, resignation, impeachment, or disability. This succession is outlined in the 25th Amendment to the Constitution. 

While the Vice President's constitutional roles are limited, their influence and responsibilities have expanded significantly over the years. The Vice President often serves as a close adviser to the President and participates in cabinet meetings and discussions on key policy decisions. They may have a significant role in shaping the President's policy agenda. 

The Vice President frequently represents the administration and the United States at home and abroad. They attend important events, meet with foreign leaders, and deliver speeches on the President's behalf. 

The Vice President of the United States holds a unique position that combines constitutional responsibilities with practical roles that can vary from one administration to another. The effectiveness and influence of each Vice President depend on their relationship with the President, their political acumen, and the demands of the time.