You can cancel an election and ban the winner from running (Romania), you can ban your opponents from ever running again (Hungary), you can threaten to ban the main opposition party and subject it to relentless investigations by the secret police (Germany), you can threaten a ban on the leading presidential candidate and make them wear an ankle monitor (France), every member of your circle can be investigated for corruption (Spain), you can try and cancel local elections because you will lose them (Britain), and you can storm the constitutional court with riot police because you want to control it (Poland).
You can just do all these things. The secret is you just have to be on the right side of the European Commission.