How is the judicial selection process a primary reason that American courts are considered political institutions?

What will be an ideal response?

An ideal response will:
1, Discuss the practice known as senatorial courtesy, where senators from the president's party have virtual veto power over potential nominees for their home state's district courts.
2, Explain that senators are also consulted on nominations for the federal court of appeals that covers their state; the judges who ultimately get selected are usually acquainted personally with the senators, active in the political campaigns of the senators and other party members, or accomplished in raising campaign funds for the party.
3, Note that presidents seek to please favored constituencies and to advance their policy preferences in choosing appointees they believe share their values; interest groups find avenues through which they seek to influence the president's choices as well as the confirmation votes of senators.