Checks and Balances in Judicial Appointments

The framers of the Constitution established a system of checks and balances to maintain a balance of power among the three branches of government: legislative, executive, and judicial. This system allows each branch to limit the powers of the others, ensuring that no single branch becomes too powerful. Consider the following scenario:

The President has nominated a candidate for the Supreme Court, but the Senate is responsible for confirming appointments. If the Senate refuses to confirm the President's nominee, what aspect of checks and balances is being illustrated in this situation?