> I mean, without a constitutional amendment how can that be done?

1. Ignore the laws passed by Congress, and rule by executive decree

2. Experience no consequences, and thereby

3. Establish and institutionalize the idea that Congress is meaningless and decorative.

What documents say the law is doesn't mean anything if it what the people with guns do doesn't reflect what those documents say.

Supremely court decisions, I think.

They have more or less done it already. Most districts are firmly in control of republicans. The congress is bound to the desires of the extreme right wing. Even the threat of impeachment is now a laughing matter from Trump after 2 such attempts going to nothing.

Yep - they just have to elect enough candidates who will let Trump run amok. The majority doesn't need to agree with Trump, just enough people to avoid voting (a much smaller number). That's what we're seeing now.

Then they just have to keep that small number of people in power through whatever means. Even if congress swings enough to have anti-Trump votes, he'll just ignore whatever Congress says, and force it into the courts (which are packed increasingly with Trump friendly judges). That's how it happens.