They can stack the court if they get a majority in both (which would increase election chances since you'd be giving people hope they won't live in a theocracy ruled an unelected supreme council. Fuck we're even less democratic than Iran on paper.), they can marginalize the court by very publicly refusing to enforce their rulings, they can have them assassinated.
The alternative is expecting to win every single election for the next 40 years or so until they die of natural causes. And then being willing to ban the filibuster to actually get a dem pick in.