This is what constitutions are for. When you have the support, you install a constitutional protection that says the government can't do this. Repealing the protection requires the same super-majority needed to pass it, so changing the law isn't just a matter of the tyrants needing to get back to 51% from 49%, they have to get from 33% to 67%.
Then you layer these protections against multiple levels of government so they'd all have to be repealed together by separate legislatures before the government is allowed to do it, discouraging the attempt.
Then you layer these protections against multiple levels of government so they'd all have to be repealed together by separate legislatures before the government is allowed to do it, discouraging the attempt.