Congress can call state ratifying conventions to amend the US constitution. We can increase the federal minimum wage and tie it to the rising cost of living and have healthcare as a basic human right. We can also ban corporate political free speech and ban gerrymandering.
In theory you could skip all the federal positions if you had enough support. It’d just be extremely hard. You would need 34 states to call for a convention, in which the federal government couldn’t say no. And any amendments ratified by 3/4 of the states would go into the constitution. Which is a lot of states, but note it also means you don’t have to have 2/3rds of the states support. You could have 51% support in 38 states and it would go through. Getting billionaires to not fund ad campaigns to fight against such happening would be almost impossible though. You’d have to have amendments that most people supported at opportune times. Like convincing people to kill citizens United because Democrats billionaires and Republican billionaires are clearly using their money to get giant sway and making individual voices worth less. Then once there, maybe get other stuff pushed through to limit lobbying. You’d have to get states pissed at the feds really.