What if the President of the US couldn't get a security clearance?

The National Security Act of 1947 requires that the President keep the oversight committees of Congress “fully and currently informed” of intelligence activities. If an intelligence agency were to try to obstruct the delivery of classified information based on who was running one of the committees, there is no doubt that they would be in violation of the law. If the President didn’t act to correct that, surely Congress could figure out some consequences, from cutting funds to impeachment of the difficult agency officials.

And again, members of Congress don’t have security clearances.

A government-lawyer friend of mine told the story of working with a military investigator who, in introducing himself, explained that he and his wife were swingers and liked to go to clubs where they could pick up a third person or perhaps another couple. Apparently whatever DOD component he worked for was trying to push this guy out, and he was making his lifestyle immediately known to others so that the agency would have no basis to assert that he was a target for blackmail. My friend said that he was an excellent investigator, but didn’t know what eventually happened to him.

I don’t doubt that a duly-elected Communist government in the U.S. could do a lot of stuff that would be ruthless, scary and tyrannical, but if we presume that they would actually obey the Constitution as written, there’s still Art. III: “…The Judges, both of the supreme and inferior Courts, shall hold their Offices during good Behavior, and shall, at stated Times, receive for their Services a Compensation which shall not be diminished during their Continuance in Office.”

If by “reduce” you mean firing, no. If you mean impeaching and removing from office, I wouldn’t be at all surprised. Historically, communist leaders tend not to get too hung up on legal niceties, to say the least.

To answer the OP: the President is entitled to know everything that’s going on in his government because he holds the executive power under Art. II, and there’s no one who can lawfully deny him the information he requests (other than information protected under Federal privacy laws like tax or medical stuff, but he wouldn’t need a security clearance for that anyway).

Good point. I also forgot about efforts to ban religion which might not go over too well.

Indeed. I know several openly gay individuals who hold Top Secret clearances.