Political career

I have a Sim that's the National Leader and I can at least go by what I have experienced:

-Promoting Policies helps to increase the success rate of securing votes
-Having a relationship up to Good Friends increases the success rate even more
-Be in a very good mood, ideally Confident
-Have very high Charisma skill, if not max

What I don't do is securing bribes, making empty promises, or debating politics on whatever Left or Right side, though I'm unsure how much that affects because they're usually more or less either more leaning to your views or not. Also, if you've found a Sim who has continually agreed to give you the vote, just keep using that Sim! Never hurts to ask the same Sim time and again anyway lol. My politician always ask his fiance to secure votes, and he's never said no yet.

Thanks, @paradiseplanet I did not know you could ask the same sims more than once - I will certainly try that. As for the tips - my sim just got turned down by his granddaughter and he was in confident mood. His charisma is maxed out and he and his granddaughter are friends (not yet good friends). Sometimes when he does not get the vote he asks for a large bribe and gets it! He always promotes his policies first and even sometimes uses flattery with some success. He even argues from the right and once views match he proceeds to ask for a vote. Even then most times it is unsuccessful. So it is very random I think.

Well I must be very lucky with mine then; oftentimes I get no's from acquaintances and even friends with about 50% friendship as well. However though even after having known the political differences with him and his political rival, Victor Feng, he even managed to secure his vote too lol.

You shouldn't even need to be friends. Just have a pleasant conversation with them, promote your politics and then secure vote.