Here, I'll lay out some of the ideas that I've come across over the years of contemplating power and democracy. Minor tweaks in the election process create vastly different outcomes. The United States has the longest running constitution in the world, and it is a testimony to the foresight of the founders that it has worked so well, for so long. But it is a big ship letting in water, slowly sinking while the people who should be fixing it are fighting with each other over who gets to be captain. There is a pessimist inside me saying that it will sink no matter what, but the optimist wrote this article.
I listed these in order of feasibility. Tweaking how primaries work is a no-brainer and easy to implement at different levels. A constitutional amendment, however, requires a proposal from two thirds of Congress (or two third of states), then ratification by three fourths of states. The chance of Congress proposing an amendment that reduces their own power is unlikely, but this is not a thought experiment in what is likely, it's a brainstorm session on a better democracy.