The stakes are so high in this presidential election for a fundamental reason that doesn't get discussed nearly enough: The federal government is so large and powerful. In particular, any aggressive president and Congress acting together have it in their legal authority -- under our presently elasticized Constitution -- to exercise near complete control over the economy. A long line of judge-made law since the Supreme Court's New Deal era decision in Wickard v. Filburn (1942) says there is almost no limit, under the commerce clause of the Constitution, to the regulatory reach of the federal government.
Thus, a united president and Congress can, as a practical matter, do all or any of the following (plus much more): take your money and give it to someone else; tell businesses what to produce and sell, who to hire and what wages to pay; set all commodity, wholesale and retail prices; control all energy supplies, communication networks and financial markets; replace all private health-care with a government system; prescribe the curriculum for all schools; determine which students get a slot in elite universities; diminish political and other speech; and enroll all citizens above the age of 17 either in the military or in civilian corps for periodic instruction and service. Children could be required to spend the summer in government "youth" camps.