Goku would trail in the Polls, on election night it would look like he was sure to fail after he loses a key swing state. Until he turned Super Saiyan and ended up with 370 electoral votes.
Superman would start a war with Iran because it's the American way. Goku would start a war with Iran because he hears they are really strong. Goku would probably reform the education system to focus on PE and combat sports, Superman's anti-billionaire bona fides are relatively strong but he is a capitalist dog at his core.
I would choose Goku as the lesser evil. Yes he'll start wars with a bunch of different countries, but he'll insist on going and fighting them himself as opposed to sending in the Marines or conducting airstrikes.
I feel like of the two Goku would be a much better candidate on the Palestine issue. Superman would team up with his Israeli colleague Sabra, Goku would look at Hamas resistance fighter strapping bombs onto tanks, remember his own battle with the red ribbon army, and go to town on the IDF.
Goku hands down. People are tired of American super heroes, and chuds probably think Goku would destroy the "Woke" because he's Asian coded and also very buff.
Meanwhile if Goku did get in he would just train and eat and leave everyone alone mostly. But also if he caught his fellow politicians doing something crooked he is the kind of guy to challenge them to a fight. While Saiyans are very "might makes right", Goku was raised by humans and at least has a very strong dislike of slavers and imperial conquerers, even other Saiyans (other than Vegeta for some stupid reason).
I could see Goku getting increasingly excited when hearing about the DPRKs military and rushing off for a fight. Goku would start a dozen wars, but he would go fight them all individually without any civilian casualties.
He would also singlehandedly end Israel's occupation.
an American presidential election? Goku isn't a citizen but because the Dems don't give a shit about DACA recipients Superman probably isn't either. So it's a tossup
Superman is the personification of the American way, so he would suppress goku’s supporters, buy off the counters, send out death squads to hunt down people campaigning for goku, and if all else fails just overthrow goku’s government.
Red Son has a movie too in which Superman (the USSR version) basically does make the world a lot better. Fucking Batman ruins everything as usual if I remember correctly... rich boy billionaire Bruce always shows up to ruin things. I'm not sure what lesson we're supposed to take from that arc. Melt billionaires with your laser eyes?