Why is the appointment of supreme court judges so controversial in the upcoming election?

Federal judge selection for the District Court, Courts of Appeals and Supreme Court are controversial because they are appointed for life during good behavior and their salaries may not be reduced during their service. These courts are called Article 3 Courts, having been created under authority of Article 3 of the Constitution. Federal judges, especially on the Supreme Court and Court of Appeals, can have a great impact on the interpretation of our laws for many years. Conservative minded Presidents and Senators want conservative minded judges just as liberal minded Presidents and Senators want liberal-minded judges. So when a conservative judge is nominated for the court and a liberal Senate has to confirm, (and vice versa) there will be controversy. There are other federal courts referred to as Article 1 courts, whose judges do not have lifetime tenure.