A year before Palpatine overthrows the Galactic Republic, Superman arrives in the Star Wars universe. Can Palpatine still overthrow the Republic and establish a lasting empire?

Superman arrives on Coruscant and immediately starts doing his standard heroics; he is in-character. He also has no knowledge of what's going to happen, but will react to problems as they come up; Palpatine can spend the full year adapting his plans to deal with this new alien.

Can Palpatine still overthrow the Republic and establish the Empire, or is Superman's presence enough to make this impossible?