To win 50%+ of the vote, all you need to do is artificially select and promote a dividing issue that gives you a 51% or more advantage among the electorate. And even then, you can import illegal aliens or manipulate immigration to socially engineer the electorate you can win with.
It is not advantageous to select an issue upon which 90% or more people agree. This is because it is not a dividing issue and doesn't give you an advantage over your political opponents.
By design, a good campaign team pushes issues that give them slight advantages over a divided people.
Politics revolves around these "wedge" issues. Insert billions of dollars of fiat currency and marketing and propaganda and you can steer the entire conversation, choose what the wedge issues are, and divide an entire populace to your will and command. Divide into republican and demoKKKrat and conquer both with propaganda designed to appeal to each group in different, but effective means. Divide the logical from the emotional, and design your propaganda to appeal to both.
I republic ISN'T supposed to better represent the 51% majority, that's the whole point of it. A republic, through intermediaries between the massed public (which is little better than a mob), should work for the greater good while generally reflecting public will through periodic elections of lesser offices that feed upwards what policy decisions should be made. But, now we directly elect Senators, the House is to small, and the vote has been given to people who shouldn't have it.
You won't see me disagree with you that the greater power in the executive branch, combined with an expanded bureaucracy, have caused massive problems and perverted the Constitution.