It actually is leverage because those people who get the most votes are in charge of our government.
The government monopoly on violence, controlled by the people who get voted in, is the clear and obvious leverage.
> Mitterrand did attempt to do the things his voters wanted. He was constrained by capitalists who punished him mercilessly until he bent the knee.
Sounds like he didn't get enough of his own people in government then.
If you fail, then it means that you didn't get enough people voted in. Having leverage requires more than just winning a single election. It involves winning many elections and getting widespread support and your people in government.