The three main powers of the president are:

1. Commander-in-Chief Power: The president has supreme authority over the armed forces, including the ability to launch and supervise military operations, order troop deployments, and direct military policy.
2. Executive Power: The president is the sole holder of the executive powers of the United States, which include managing national affairs, setting government priorities, issuing executive orders (which have the force of law without needing Congressional approval), appointing and removing executive officers including cabinet members and federal judges (with Senate approval), and preparing the federal budget.
3. Legislative Power: The president interacts with Congress in shaping laws, including the power to sign bills into law or veto them, issue signing statements expressing interpretations of bills, propose legislation (such as in the State of the Union address), and call special sessions of Congress if needed.

These powers collectively enable the president to direct military policy, manage the government, and influence the legislative process, all while being balanced by the other branches of government through checks and balances.