You can't select proposal that would require more money of what you have at your disposal in that moment : )
Like in many strategy games, you have an amount of money that you receive for each turn, or event in this case, and at the start that amount is positive (think of it like taxes for example). But, like said at the start of the game, some of your decisions may have long lasting effects, so you could end up losing money instead of making them.
The game was made to be tricky, as the message of it is that being a mayor of a city and try to find a balance between politics and helping the environment is not at all easy, as sometimes people may want what's actually not best of them. You may have to replay the game a couple of times to actually unlock the winning condition.
I realise that the game is rough around the edges, but that's because it was made during a game jam in a very small amount of time, so think of it more like a proof of concept more than anything else. We may update it in the future to add more features that we simply didn't have time for.
Thank you very much for playing the game and also taking the time to leave some feedback!