Step 1: Hire ~100 thugs to disrupt polling locations in key states. A few thugs are apprehended, but there is no clarity as to who hired them, motivation, etc.
Step 2: Ensure that the footage of these thugs is widely disseminated, through a partisan major media network. The other networks follow suit, but there will be no clarity about the nature or purpose of the thugs.
Step 3: Trump and friends use this thuggery as an excuse to declare the election invalid or otherwise in dispute. They take it to the Supreme Court.
Step 4: After whatever period — days, weeks, months, years — the Supreme Court either declares the election valid in favor of keeping Trump in office. Hotly disputed, it’s a 5–4 partisan vote, with Bush v. Gore cited as a key precedent by the majority.
Step 5: California, New York, and a few other states jointly declare that they will withhold payments to the Federal government in protest over the clearly partisan nature of the Supreme Court ruling.
Step 6: Trump orders US Troops to occupy State government buildings until payments are restored. Tensions run high. Nobody knows who fired the first shot.
Step 7: Well, shit. The theme song for the next decade is a loop of Putin endlessly laughing.