This happens in fiction a lot, (American fiction at least), a high level US politician or even the US President promises somebody something for their help/cooperation.
I’m curious if say the US President promises to give you a great job with full benefits if you were to vote for him, could you say get a lawyer to write you up a contract to ensure the President just doesn’t fire you/lay you off after he gets what he wants? Or say you somehow get Congress or The Senate to pass a motion to ensure you keep the job for 10 years? Legally speaking of course no discussion of secret assassinations or jailing.
No. Leaving aside evidentiary problems (how are you going to prove you voted for him?) you have the problem that the contract is unlawful as being contrary to public policy — it’s fundamentally corrupt. And you can’t enforce an unlawful contract.
From the contract law perspective, I think campaign promises fail to constitute a binding contract on a very fundamental level: Lack of intention to create legal relations.
I would wonder what role promissory estoppel plays in this. In some civil cases, if someone promised something to you, and you relied on it in good faith (detrimental reliance) and suffered harm when the promise was not fulfilled, you have some standing to claim damages/rectifying of the wrong that was done.
In general, yes, they do. But the OP postulates that the promise is embodied in a professionally drafted written contract, which I think would probably establish the intention to create legal relations. Even in that case, I still think enforcement would be impossible on the public policy ground.
As @Northern_Piper points out, there may be a difference under local law if the thing promised was a government job or was something else.
I’m not sure selling your vote is illegal. It ought to be. Pretty good bet buying your vote is illegal. Such that any contract based on that illegality is itself illegal.
I recall some case in one province where someone was prosecuted for paying another person to run against another party’s candidate, hoping to split the ethnic vote or something.
I’ve always understood paying people (or other consideration) to vote for you was illegal. I’d be surprised if that is not the case in the USA also.
As I read the OP, the hypothetical contract doesn’t say anything about buying or selling a vote (even though that may have happened behind the scenes). The contract merely says that a person won’t be fired from their job for a specified period of time. IANAL but that seems perfectly legitimate to me.
For arguments sake, let’s say the politician gave you a promise in writing. A contract.
But, the politician cannot deliver on the promise once in office. They tried, but the (say) governor would not sign the bill or she could not round-up the necessary votes in the legislature.
Is the politician still on the hook or can they say they did their part but other things beyond their control made it impossible to meet the terms of the contract?